Microsoft’s New Email Rules: SPF, DKIM, DMARC or Bust (A CISO’s Sarcastic Guide)

Antonio Ieranò 07/11/2025 AI Tech Update, Tech Update in English

originally posted non linkedin: https://www.linkedin.com/pulse/microsofts-new-email-rules-spf-dkim-dmarc-bust-cisos-sarcastic-ipp4f/?trackingId=ax49582QQsmt8%2FZStLd3GQ%3D%3D

🚨 I told you so. 🚨
Yes, I did say this was coming. Loud and clear. But apparently, the gentle whispers of SPF, DKIM, and DMARC weren’t enough to wake those still snoozing in the warm blanket of “we’ll fix it when it breaks.”
Well, guess what? Microsoft has joined the SPF-DKIM-DMARC enforcers club, right next to Google, Yahoo, and Apple. And this time, it’s not just polite suggestions. It’s “comply or good luck reaching the inbox.”
Still waiting for a disaster to act? Don’t worry — NIS2 is just around the corner to give you a regulatory wake-up slap. Because nothing says “urgent” like an EU directive and your emails bouncing into the abyss.
📣 Attention CISOs, Marketing folks, and Compliance teams: consider this your final boarding call to Email Authentication Central. Or keep dreaming — until your next big campaign lands straight in Junkville.
I’ve written a light-hearted, sarcasm-laced deep dive (yes, it’s long — knowledge weighs a bit).
Enjoy the read, and hey — maybe this time, we’ll prepare before the fire starts. 🧯🔥
👉

Email still reigns as the business communication king – and also the king of spam and phishing. In a move that has many CISOs saying “finally!” (and a few saying “oh no, not another project”), Microsoft announced new email authentication requirements for high-volume senders. In plain English: if your organization sends a lot of emails, you’d better have SPF, DKIM, and DMARC properly set up, or your messages might end up in the junk folder by default techcommunity.microsoft.com and techcommunity.microsoft.com. Microsoft is not alone here; Google, Yahoo, and even Apple are on the same bandwagon of enforcing email authentication for bulk senders proofpoint.com and proofpoint.com. In this article, we’ll break down what’s happening, why it’s happening now, and how to survive this with your email reputation (and legal compliance) intact – all with a light dash of sarcasm to keep things interesting.

Agenda – What We’ll Cover

New Email Authentication Mandates – A brief overview of Microsoft’s announcement (SPF, DKIM, DMARC for high-volume senders) and how it aligns with similar moves by Google, Yahoo, and Apple.
“Why Now?” (Humorous Edition) – A tongue-in-cheek look at why these changes are coming at this point in time and what could happen if you pretend none of this is happening.
How to Comply (Aligning SPF, DKIM, DMARC) – Detailed guidance on getting your email infrastructure in order, including what “alignment” means in DMARC-world and why it matters.
Special Cases: Apps, Automation, and SaaS – The challenges of emails sent by printers, apps, and third-party platforms (rather than humans hitting “Send”), and recommendations to keep those compliant too.
Enter the Regulators: NIS2 and Legal Implications – How these email requirements intersect with the EU’s NIS2 directive (and other regulations), and why ignoring email security could land you in hot water legally.
The EU Complexity Puzzle – Analysis of the extra complexity EU-based organizations face when juggling technical requirements and legal obligations simultaneously.
Real-World Analogies & Examples – A few relatable examples (and maybe a superhero analogy or two) to make the tech easier to digest, plus a quick recap and next steps.
References & Resources – A list of official documentation, best practice guides, and frameworks for further reading (for when you need to convince your team or auditors that you’re not making this stuff up).

Alright, let’s dive in – cape on, sarcastic quips at the ready.

1. Outlook’s New Requirements for High-Volume Senders (And the Industry Trend)

In early April 2025, Microsoft dropped the news: Outlook.com (the consumer Outlook/Hotmail/Live services) will start enforcing strict email authentication for any domain blasting out over 5,000 emails per day techcommunity.microsoft.com. In Microsoft’s own words, for those high-volume domains, messages must pass SPF and DKIM, and be aligned with a DMARC policy (at least p=none) techcommunity.microsoft.com. If not? Initially, those emails get shunted to the Junk folder as a warning shot. Eventually, Microsoft will outright reject emails from non-compliant senders – essentially saying “if you won’t authenticate, we won’t deliver” techcommunity.microsoft.com and blog.redsift.com.

This move by Microsoft isn’t happening in isolation. It aligns with similar policies announced by Google’s Gmail and Yahoo Mail in late 2023. Gmail and Yahoo both decided that starting February 2024 any sender pumping out more than 5,000 emails a day to their users must have proper SPF, DKIM, and a DMARC policy in place (along with some list management best practices like easy one-click unsubscribe) proofpoint.com and proofpoint.com. In fact, Google explicitly requires bulk senders to ensure SPF/DKIM “alignment” and publish a DMARC policy, or risk seeing their emails blocked or spam-foldered proofpoint.com. Yahoo mirrored these requirements on the same timeline, aiming to reduce spoofing and cut down “low-value emails” cluttering inboxes proofpoint.com.

And let’s not forget Apple’s iCloud Mail. While Apple didn’t issue a dramatic deadline, they quietly published an email best practices guide urging senders to adopt SPF, DKIM, and DMARC. Apple basically said, “If you want your bulk emails delivered to iCloud users and not auto-blocked as junk, you should really be using these authentication standards.” In fact, Apple’s postmaster page flat-out says “the sending domain must publish their DMARC policy” and to make use of SPF and DKIM support.apple.com. (Translation: do it, or expect trouble delivering to @icloud.com addresses). Apple’s stance came shortly after Google and Yahoo’s announcements, reinforcing that all major email providers are now singing from the same hymn sheet proofpoint.com.

So in summary, the email ecosystem’s big players have collectively raised the security bar. Microsoft was actually a tad late to the party (perhaps enjoying watching others be the bad cop first), but with Outlook.com enforcing these rules from May 2025 onward, it’s official – the era of “optional” email authentication for mass senders is ending. If you’re a high-volume sender (think marketing newsletters, notifications to lots of customers, etc.), SPF, DKIM, and DMARC are no longer just best practices – they’re requirements T echcommunity.microsoft.com and blog.redsift.com. And even if you send less than 5,000 emails/day, don’t get complacent: the writing is on the wall that eventually these security checks could become table stakes for everyone. As Microsoft’s FAQ gently hints, “while enforcement first targets large senders, all senders benefit from these best practices”

techcommunity.microsoft.com. In other words: Don’t say we didn’t warn you.

2. Why Now? (Or: Email’s Been Around Since Forever – What Took So Long?)

You might be thinking, “Email authentication isn’t new – SPF has been around since the early 2000s, DKIM since 2007, and DMARC since 2012. Why are the email giants getting strict now, in the mid-2020s?” Great question. Let’s take a lightly sarcastic stab at the reasons:

Because Phishing Isn’t Going Away – Every year, phishing and spoofing attacks break new records. It turns out letting emails through that claim to be from your bank or CEO (but aren’t) is a bad thing. Who knew? Google, Microsoft, Yahoo, etc., have finally decided that maybe we should actually enforce the tools designed a decade ago to stop spoofing. As one industry pundit might put it: Better late than never, guys! These moves are explicitly to “stem the flow of malicious messages” and protect users from phishing and spam proofpoint.com and techcommunity.microsoft.com. In corporate speak, they are “raising the bar to inspire lasting change” techcommunity.microsoft.com. In plain speak, they’re tired of being the delivery service for phishers.
Everyone Else Is Doing It – There’s a bit of email peer pressure here. Google and Yahoo made the first move in 2024, likely prompting Microsoft to follow suit so Outlook isn’t seen as the easy target for spoofers. Apple chimed in with support. Now it’s a unified front. Nobody wants to be the last free-for-all spam haven. So it’s a coordinated industry effort: if all major inbox providers demand authentication, the bad guys have fewer holes to exploit. Microsoft openly acknowledges pushing “the broader industry toward best practices” and that by raising requirements for big senders, it “benefits everyone” techcommunity.microsoft.com.
User Complaints and Brand Protection – Users are fed up with inboxes full of junk, and companies are fed up with scammers impersonating them. These new rules promise “stronger brand protection and better deliverability” for legitimate senders techcommunity.microsoft.com. And frankly, the inbox providers are fed up too – if senders won’t police themselves, the providers will do it for them. Think of it as the email equivalent of a city finally enforcing long-ignored littering laws because the streets got that dirty.
Regulatory Nudge – Though not explicitly stated by Microsoft or Google, there’s likely a compliance undertone. With new cybersecurity regulations (hello, EU NIS2 – we’ll talk more about you later) and governments urging stronger cyber hygiene, big tech companies know that cracking down on email abuse is the “right thing” to do (and it avoids awkward conversations where regulators ask “why didn’t you do more to stop those fake emails?”). There’s even speculation that not having DMARC could be seen as negligence under emerging laws redsift.com and redsift.com. So the timing aligns with a broader push for accountability in cybersecurity.

Now, what happens if organizations don’t comply with these new requirements? In short: nothing good. Here’s a preview of the likely outcomes (sprinkled with humor, because you’ll need it):

Spam Folder Doom – Microsoft has made it clear: miss the SPF/DKIM/DMARC trifecta and your messages will be banished to the Junk folder techcommunity.microsoft.com and techcommunity.microsoft.com. At first, it’s “just” junk mail handling – your email technically gets delivered, but your recipient never sees it unless they obsessively check spam (which most normal humans don’t). This means your carefully crafted marketing campaign or that big customer announcement might as well be whispered into a void. Not great for business, right?
Eventually, Bounce-ville – After a grace period of nagging you via the spam folder, the providers will escalate to outright rejection of your emails techcommunity.microsoft.com and blog.redsift.com. That means you’ll start getting bounce-back error messages saying your email was refused due to failed authentication. Picture your email server trying to deliver messages and Gmail replying with “Nope. Not taking it. You’re not authenticated, go fix your stuff.” It’s like being unceremoniously kicked out of the post office line because you didn’t put a stamp on the letter.
Brand and Reputation Damage – Today, if your emails aren’t authenticated, savvy recipients might see warnings like “This message could be spoofed” or question marks on the sender name in email clients. Going forward, if you get flagged under these new rules, your domain’s reputation with email providers will tank. It’s akin to being put on a naughty list. Restoring a damaged email reputation can be slow and painful – it’s far better not to lose it in the first place. As Microsoft notes, compliant senders get “stronger brand credibility” and improved deliverability techcommunity.microsoft.com. The unspoken flip side: non-compliant senders will be viewed with suspicion.
Internal Fallout – Let’s not underestimate the human drama. If you ignore these requirements, one morning your CEO might call the CISO/CIO in a panic because none of the 50,000 customers who were supposed to get the new product announcement email actually saw it. Or your marketing team will burst into your office, saying the latest campaign’s open rates fell off a cliff. You really don’t want to be the person explaining “Oh, sorry, our emails are all going to spam/rejected because we didn’t implement that ‘DMARC thing’ everyone told us about.” Awkward! In short, non-compliance could make you very unpopular in your organization.

To sum up: these changes are happening now because the email ecosystem reached a tipping point where doing nothing was no longer an option. And if you don’t comply, you risk having your communications crippled. Or as one security blog bluntly put it, “Ignoring today’s new requirements could result in email deliverability issues, spam filtering, or outright rejection” blog.redsift.com. In other words, play by the new rules or your emails might just vanish into the ether.

So, now that we (hopefully) agree compliance is not optional, let’s talk about how to actually get compliant.

3. How to Align Your Email with SPF, DKIM, and DMARC (A Crash Course)

It’s time to get technical (but we’ll keep it digestible). The trio of SPF, DKIM, and DMARC can sound like a bowl of alphabet soup, so let’s clarify each and explain what “alignment” means. By the end of this section, you’ll have a to-do list for making your email setup satisfy the new requirements. (Cue the superhero theme music as we introduce our three heroes: SPF, DKIM, and DMARC…)

SPF, DKIM, and DMARC: The heroes of email security. Each “hero” plays a unique role in protecting your domain’s emails from impersonation and tampering.

SPF (Sender Policy Framework) – The Bouncer. SPF is essentially a DNS record that says “Here are the servers allowed to send email for my domain.” Think of it as the guest list at a club – if your email didn’t come from an IP address on the list, the receiving mail server can say “sorry, you’re not on the list” and treat the email suspiciously. Under the new rules, your SPF must pass for your domain’s outgoing emails techcommunity.microsoft.com. This means:

You need to publish an SPF record in your domain’s DNS. It’s a TXT record that starts with v=spf1 and then lists authorized sending servers (by IP or include statements for third-parties). For example: v=spf1 include:mail.yourcompany.com include:sendgrid.net -all. The -all at the end means “hard fail if not matching these.”
Make sure it’s accurate and up to date. Inventory all the systems that send email as your domain (your primary mail server, marketing platforms, CRMs, etc.) and ensure they’re covered in the SPF. Nothing undermines SPF like forgetting to include that new cloud service that sends invoices on your behalf.
Watch the 10 lookup limit: SPF has a quirky limitation – the receiving server will only do 10 DNS lookups while evaluating your includes. If you nest too many includes (by using many third-party services), you could exceed the limit and your SPF fails by default. Microsoft even highlights this in their FAQ: going over 10 lookups can cause SPF to fail techcommunity.microsoft.com. The fix is to simplify (there are tools to “flatten” SPF records if needed).

In short, SPF passing means the server that sent the email is authorized in DNS. Under DMARC, it also must be aligned (more on alignment in a moment), meaning the domain in the email’s return-path (envelope sender) matches your actual domain. We’ll circle back to this alignment concept after defining our other heroes.

DKIM (DomainKeys Identified Mail) – The Cryptographic Signature. DKIM is like a wax seal on a letter’s envelope – it proves the contents haven’t been tampered with and that the sender is legitimate. In practice, DKIM works by having your sending mail server attach a digital signature to each outgoing email’s headers. This signature is generated with a private key that only you have, and the receiving server checks it using a public key you publish in your DNS. If the math adds up, the email hasn’t been altered and truly comes from a domain that holds the matching private key. The new requirements say DKIM must pass to validate email integrity and authenticity techcommunity.microsoft.com.

Key steps for DKIM:

Enable DKIM signing on all your mail sources. Many email systems (Office 365, Google Workspace, mail gateways, etc.) can handle DKIM signing – often it’s just a matter of turning it on and adding the provided DNS record. For example, Microsoft 365 gives you two CNAMEs to publish, which then allow Microsoft to sign your emails with DKIM. Other systems might give you a public key to publish in a TXT record (commonly at a selector like selector1._domainkey.yourdomain.com).
Use 2048-bit keys if possible. (A bit of best-practice advice: use strong keys and rotate them annually or so). But no need to overdo it in this article – just ensure DKIM is in place.
Verify the signature is working. You can send a test email to a Gmail or other account and check the email headers to see if DKIM=pass. (There are tools and Gmail’s web interface which show this in the raw message headers.)

DKIM is wonderful because it sticks with the email even if it’s forwarded (unlike SPF, which can break on forwarding). It “travels” with the message as a cryptographic assurance. However, out of the box DKIM doesn’t tie that assurance to the visible sender’s domain – that’s where DMARC comes in.

DMARC (Domain-based Message Authentication, Reporting, and Conformance) – The Policy Enforcer. DMARC builds on SPF and DKIM by adding the concept of alignment and by telling receivers what to do if authentication fails. It’s essentially you (as a domain owner) saying: “For any email claiming to be from my domain, it better pass SPF and/or DKIM checks in alignment with my domain. If not, here’s what I want you to do (nothing, quarantine it, or reject it). And please send me reports so I can see who’s misbehaving.”

Under Microsoft’s new rule, domains should have at least a DMARC policy of p=none (monitoring mode) with proper alignment techcommunity.microsoft.com. In other words, publish a DMARC record for your domain, even if initially you’re just monitoring (p=none). Google and Yahoo’s requirements similarly demand a DMARC policy be in place proofpoint.com.

So how do you get DMARC going?

Publish a DMARC DNS record for your domain (and any domain that sends email). The record goes at _dmarc.yourdomain.com and might look like: v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com; ruf=mailto:yourdomain@forensics.dmarcservice.com; fo=1. Let’s break that down: p=none means “monitor only, don’t actually quaranrine/reject yet.” Eventually you’d change that to p=quarantine or p=reject to enforce protection once you’re confident. The rua is where aggregate reports go (daily XML summaries of authentication results). The ruf is for forensic/failure reports (sometimes redacted copies of emails that failed; not all receivers send these). fo=1 just means send forensic reports on any failure (one of several flags you can tweak).
Alignment requirements: By default, DMARC is satisfied if either SPF or DKIM passes in alignment. Alignment means the domain in the From: header (what users see) matches the domain that was validated by SPF or DKIM. There are two modes: “relaxed” (the domains can be subdomains or organizationally related) and “strict” (must match exactly). Most use relaxed alignment, which is fine. For example: If your email is from newsletter@news.company.com and your DKIM signature domain is news.company.com, that’s aligned (exact match). If DKIM passes, DMARC passes. If your email from is sales@company.com and the SPF check passes for company.com (meaning the bounce/return-path was something@company.com), that’s aligned on SPF. If the domains don’t match – e.g., your email says it’s from @company.com but actually was sent via a third party using their own domain in the bounce address and no DKIM for yours – then DMARC would fail (no alignment).

Microsoft’s FAQ puts it succinctly: “Alignment ensures the ‘From’ domain matches (or is a subdomain of) the domain used by SPF and/or DKIM. This prevents bad actors from exploiting your domain name.” techcommunity.microsoft.com.

So to comply, you need to configure SPF and DKIM such that at least one of them ties back to the domain in your From address. Ideally, do both – that’s what “alignment with either SPF or DKIM (preferably both)” means techcommunity.microsoft.com.

Start with p=none: This will not affect delivery but will let you collect DMARC reports. Review the reports to see where emails are coming from and which ones would fail. This helps catch any forgotten senders or misconfigurations.
Move to enforcement (quarantine/reject) once ready: Ultimately, the goal (from a security standpoint) is p=reject – that’s when you’re saying “if it’s not authenticated properly, straight up reject it.” That provides the strongest protection against spoofed emails using your domain redsift.com and redsift.com. But you should only do this once you’re sure all legitimate mail streams are authenticating OK, to avoid blocking real mail. Microsoft (and others) aren’t requiring reject (yet), but they definitely want you on the path. Google and Yahoo, for example, say just having the policy (even if none) and alignment is the baseline proofpoint.com. Over time, expect that bar to rise.

To summarize the compliance steps, here’s a quick checklist:

SPF: Publish or update your SPF DNS record. List all sending services. Check that emails from your domain result in SPF=pass on the other end. (Use tools or Gmail’s headers to verify). Keep an eye on the 10-domain lookup limit – use includes wisely or flatten if needed techcommunity.microsoft.com.
DKIM: Enable DKIM signing on all platforms that send mail for you (your mail server, marketing platforms, etc.). Publish the public keys in DNS. Then send test messages and verify DKIM=pass on recipients. Each sending source might have its own DKIM “selector” (e.g., selector1 or s1); that’s normal.
DMARC: Publish a _dmarc DNS record for your domain with p=none and your email (or a mailbox you set up) to receive reports. This tells the world “I care about DMARC, send me data.” Over a few weeks, watch those reports (you can use a DMARC report analyzer tool or service to make it easier – otherwise you’ll be reading XML). The reports will show you any sources failing. Fix those sources (by adding them to SPF or DKIM signing). Once virtually all your legitimate mail is aligned and passing, consider switching to p=quarantine (and eventually p=reject), so that any spoofed mail claiming to be you gets zapped.
One-click unsubscribe & other hygiene (for bulk mail): If you’re sending marketing or newsletter type emails, the new rules from Gmail/Yahoo also insist on easy unsubscribe links proofpoint.com. Microsoft also “recommends” functional unsubscribe and good list hygiene techcommunity.microsoft.com. This isn’t directly about SPF/DKIM/DMARC, but it’s related to being considered a reputable sender. So ensure you include those unsubscribe headers or links, and clean out people who never engage or bounce – it’ll help keep spam complaint rates low (Google set a threshold of 0.3% complaint rate) proofpoint.com. In short, good mailing practices + authentication = you get to keep reaching your audience.

Now, a brief analogy to tie it together (because sometimes that helps when explaining to non-technical stakeholders):

Imagine Postal Mail: SPF is like putting your company’s return address envelope on every mail and having the post office verify that the letter indeed came from a permitted office location. DKIM is like stamping the letter with a special company seal that would break if the letter was opened and re-sealed – the recipient can verify the seal to ensure the contents weren’t changed and it indeed came from you. DMARC is like registering a policy at the postmaster general’s office saying “if you get a letter claiming to be from my company without my return address or without an intact seal, either trash it or send it to the dead letter office – and let me know about it.”

When all three work in harmony, the receiving mail system has high confidence the message is legit: it knows you authorized the sender (SPF), it knows the message wasn’t altered and is tied to your domain (DKIM), and you, the domain owner, stand behind it with a policy (DMARC). That’s exactly what mailbox providers want to see – and now will demand to see for big senders. As a bonus, you get protection from bad guys spoofing your domain, and your emails are more likely to hit the inbox rather than get flagged.

By the way, implementing these might sound complex, but plenty of tools and services exist to help. Many companies use DMARC reporting tools to make sense of those XML reports and even services that can manage your SPF/DKIM/DMARC records (especially useful if you have many vendors – they prevent that 10 lookup issue by consolidating includes). The key is to get started now, before the enforcement dates hit. Microsoft explicitly urges senders to “Prepare now: audit your DNS records (SPF, DKIM, DMARC) and verify you meet all the requirements” techcommunity.microsoft.com. Waiting until your emails bounce is a recipe for emergency mode (and unhappy colleagues).

So, our three heroes SPF, DKIM, and DMARC are ready to save your email – provided you actually call them to duty. Next, we’ll address a tricky area: those emails your company sends that aren’t from a person hitting “Send” in Outlook, but from apps, copiers, or third-party services. Those can be a pain if not handled right – let’s tackle that.

4. Challenges with Applications, Automated Systems, and SaaS Senders (and How to Fix Them)

It’s one thing to set up SPF/DKIM/DMARC for your primary email flow (like all the emails your employees send via Microsoft 365 or your mail server). That you can usually handle by configuring your main mail platform. But what about all those other emails your domain sends? You know, the ones from systems and machines: the automated reports, the no-reply alerts from your ERP, the marketing blasts from that cloud service your marketing team adopted, the customer emails sent via your CRM platform, the password reset emails from your website, the printer/scanner in the office that emails PDFs, etc. Many organizations have dozens of these miscellaneous email sources. They often use different infrastructure and might not have been set up with authentication in mind. Under the new rules, every single one of these sources needs to be authenticated properly or they jeopardize your compliance (and email deliverability).

Here are the common challenges and how to address them:

Third-Party Email Services (SaaS): Perhaps you use a service like Mailchimp, SendGrid, Salesforce, HubSpot, Zendesk, etc., which sends emails that appear to come from your domain. By default, many such services either send as a subdomain of their own (like yourcompany@mailchimp.com) or they ask you to verify your domain and set up DNS records. To make these compliant: Set up custom DKIM: Most reputable email platforms allow you to configure DKIM for your domain. For example, SendGrid lets you set up a DKIM (they call it domain authentication) by adding CNAMEs or TXT records. Do this for each service: it ensures the emails it sends on your behalf are signed with your domain’s key, which will align with your domain in the From address (DMARC happy). Include them in SPF: Add the service to your SPF record (usually they provide an “include:service.com”). Be cautious – as noted, too many includes can break SPF. If you have a ton of SaaS senders, you might need to consolidate or use subdomains (more on subdomain strategy in a second). Use subdomains for different services: This is a pro-tip. Let’s say you have marketing emails sent by Mailchimp and transactional emails (receipts, OTPs, etc.) sent by SendGrid. Consider using distinct subdomains: e.g. news.yourcompany.com for marketing and notify.yourcompany.com for transactional. That way, you can publish separate SPF/DKIM/DMARC records for each subdomain if needed, and it isolates risks. It also means if one service has an issue, it doesn’t spill over to all email. DMARC can be set at the subdomain level overriding the parent. Vendor doesn’t support DMARC alignment? Push them or drop them! Occasionally, you’ll encounter a vendor that says “SPF and DKIM are optional” or they sign with their own domain and don’t offer custom DKIM. In 2025, that’s not acceptable for high-volume email. You may need to push them to support these standards or consider switching to a service that does. Some older systems might only do SPF and not DKIM, or vice versa. You really want both, but at minimum one aligned method must pass. If a vendor can’t meet at least one, that’s a big problem under these new rules. As an example scenario: a third-party might send emails as no-reply@yourcompany.com from an IP not in your SPF and they don’t/can’t sign as yourcompany.com (maybe the DKIM is theirsystem.com) – those emails will fail DMARC. The solution could be to change the from address to a subdomain that they do control (less ideal for branding) or get them to support proper DKIM for your domain. There’s no magic – someone has to fix something or those emails get binned.
Internal Systems and Appliances: Think of things like your multifunction printer that scans to email, or your on-premises software that sends out alerts (backup notifications, etc.). Often these are set to use an internal SMTP server or relay. The best practice here is to have them relay through your authenticated email server if possible. For example, have your scanner send through Office 365 or through your mail gateway, so that it will get DKIM signed and come from an IP in SPF. If that’s not possible and they send direct, then you must treat them like any other sending service: give them an SPF include (e.g., include the IP in your SPF) and if feasible, have them DKIM sign. Some appliances actually let you import a DKIM key – if not, SPF might be your only hope for them. Keep track of all these little rascals; DMARC reporting will help identify them because you’ll see their IPs show up.
Emails from Cloud Applications: Many cloud services (even those not primarily email services) send email on your behalf – e.g., an HR system sending offer letters, a monitoring tool sending alerts. The challenge is similar: you need to find out how those emails are sent (from what domain/IP) and align it. This usually means reading the documentation or admin settings for each app. As tiresome as that may be, it’s now part of the job. The new rules basically force you to do a thorough inventory of all email senders. The good news is once done, your security posture improves – you’ll likely uncover some “shadow IT” services you didn’t even know were sending email as your domain redsift.com. DMARC reports can reveal “mystery senders” – maybe some old script or a forgotten system still firing off emails. You can then shut it down or authenticate it. This visibility is actually a nice side benefit of DMARC: it shines a light on all the legit (and not legit) sources using your domain.
Forwarding and Mailing Lists: This is a slightly different scenario, but worth a mention. Sometimes an email that was perfectly authenticated can fail DMARC when forwarded. For instance, Alice at company1 sends an email to Bob at company2. Bob has an automatic forward to his Gmail. Gmail sees a mail from company1 coming via company2’s servers – the SPF will fail (since company2 isn’t in company1’s SPF), and DKIM might fail if the forwarding altered the message (like a mailing list adding a footer). DMARC would fail in that case because alignment is broken through no fault of the original sender. To address this, a standard called ARC (Authenticated Received Chain) was developed. Microsoft even recommends using ARC for scenarios like forwarding and mailing lists techcommunity.microsoft.com. ARC allows the forwarder to attest to the original auth results, so the final recipient can see “it was OK when it passed through company2.” If you operate any mailing lists or forwarding services, consider enabling ARC. The mailbox providers (like Gmail, Outlook) are getting better at honoring ARC to not penalize forwarded mail. This isn’t something an average company needs to implement on their own (unless you run your own mail server and have forwarding); it’s more for the mail server administrators to be aware of. Still, it’s part of the broader picture of making sure legitimate mail isn’t mistakenly zapped by these strict policies.

In practical terms, handling the edge cases often boils down to two strategies: coordination and segmentation. Coordination with every team or vendor that sends email for you (to ensure they implement SPF/DKIM for your domain), and segmentation by domain or subdomain (so that you can manage certain email streams separately if needed, e.g., give a vendor its own subdomain to send from, isolating it from your primary domain’s policy).

Let’s illustrate with a real-world styled example:

Example: Your company, Acme Corp, uses Office 365 for employee email (which by default covers DKIM/SPF for @acme.com when properly set). Marketing uses Mailchimp to send newsletters from marketing@acme.com. Your IT team uses PagerDuty, which sends alerts from acme.pagerduty.com (a subdomain by PagerDuty). HR uses an application that sends from hr@acme.com via the app’s servers. And a legacy Oracle system in your data center sends from noreply@acme.com via its own SMTP on an old appliance.

To comply: You’d enable DKIM in Office 365 for acme.com (two DNS CNAMEs). Add Mailchimp’s include to SPF and publish a DKIM key Mailchimp provides (so Mailchimp emails pass DKIM as acme.com). For PagerDuty, maybe it’s using their subdomain, which might pass DKIM on their side – those might actually show as from: acme.pagerduty.com which is a subdomain of yours; you’d publish a DMARC for the subdomain too. The HR app – you discover it’s using some cloud IPs; you generate a DKIM key pair, give the public key to the HR app team to install if possible, or at least include its IP in SPF. The Oracle system – since it’s internal, you configure it to relay through Office 365 (authenticating with SMTP auth), so it gets signed, or if not possible, you at least include its IP in SPF (less ideal if it’s a static office IP).

Finally, you monitor DMARC reports and see everything aligning except one odd sender – turns out Finance was testing a new tool that started emailing clients without telling IT. The reports caught it, and you take action to bring it into compliance. Acme Corp then confidently moves DMARC to quarantine knowing all bases are covered.

It’s a lot of detail, but the takeaway is: Identify every source of email and ensure it’s authenticated and aligned. Create internal guidelines so that no team introduces a new email-sending service without looping in IT/security to set it up correctly. This may be a cultural change; previously, someone might plug in a new SaaS and just start emailing customers from it. Now, that’s a potential outage or compliance issue if not handled right. Use this enforcement push as an opportunity to get organizational buy-in that “email is a critical asset; we can’t just send it from anywhere willy-nilly.”

One more thing: testing and tools. Utilize tools like MX Toolbox, DMARC Analyzer, or Outlook/Google’s message header analyzers to test emails from each source. When you send a test email to Gmail, you can look at “Show Original” and see Authentication-Results: which will clearly show SPF, DKIM, DMARC pass/fail. This immediate feedback is super useful when tweaking configurations. Keep iterating until all emails you test show green lights on auth.

Alright, with the technical heavy-lifting discussed, let’s zoom out to the bigger picture: the regulatory environment that’s nudging everyone towards better email security, and why you can’t ignore that angle either (especially if you’re in the EU).

5. The Regulatory Angle: NIS2 and Why Failing at Email Security Could Cost You

Just when you thought this was only about appeasing Gmail and Outlook, here come the regulators to up the stakes. Enter NIS2, the EU’s Network and Information Security Directive 2. If your organization is based in the EU or does business there, you’ve probably heard the rumblings about NIS2 requiring stronger cybersecurity practices across many sectors. So how do these new email authentication requirements intersect with NIS2 and other laws? In a nutshell, they reinforce each other: what’s a best practice from a technical standpoint is increasingly becoming an expectation (or even requirement) from a legal standpoint.

First, a quick primer on NIS2 for context: It’s an EU directive (Directive (EU) 2022/2555) aimed at achieving a high common level of cybersecurity for organizations that are “essential” or “important” (think critical infrastructure like energy, healthcare, finance, as well as many digital services). It mandates that these entities take appropriate cybersecurity measures, do risk management, handle supply chain security, report incidents, etc. While NIS2 doesn’t explicitly list “Thou shalt implement DMARC” (it’s technology-neutral in text), it does set out broad requirements that imply you need to secure all threat vectors – and email is definitely one of the biggest threat vectors.

Key points relating to email and NIS2:

“Security by Design and Default”: NIS2 requires providers of certain services to implement cybersecurity measures by design and default redsift.com. In plainer terms, you should be proactively building security into your systems, not slapping it on later. Email authentication (SPF/DKIM/DMARC) is a great example of a security-by-design control for your communication channels. If a breach or major phishing incident occurs and it comes to light you hadn’t bothered with basic email auth, that would look pretty bad under the lens of “by default” security.
Risk Management and Incident Prevention: Organizations must take appropriate and proportionate technical measures to manage risks (Article 21 of NIS2). Considering that phishing and email spoofing are high on the list of risks (often leading to incidents like ransomware or fraud), implementing DMARC with enforcement can be seen as a “proportionate technical measure” to manage that risk. In fact, analysts have noted that the absence of a DMARC reject policy could weaken compliance with several NIS2 requirements or principles redsift.com because it leaves a well-known risk (email spoofing) insufficiently addressed. Conversely, a strong DMARC policy aligns with NIS2’s requirements as a key measure to counter phishing and spoofing redsift.com.
Supply Chain Security: NIS2 puts emphasis on securing not just your org, but also your supply chain and vendors redsift.com. Email is often a weak link in supply chain attacks – think of scenarios where a supplier’s email is spoofed to trick you, or your domain is spoofed to trick a customer or partner. By implementing DMARC at a reject policy, you ensure that only authorized third parties can send on your behalf, helping to prevent impersonation attacks via your domain redsift.com. This directly ties into supply chain security: you’re protecting your partners and customers from fake emails that appear to be from you. If an incident happened where someone spoofed your domain to hack a business partner, and you hadn’t bothered with DMARC, that could raise compliance questions under NIS2’s supply chain risk management provisions.
Incident Reporting and Damage: Under NIS2, certain incidents have to be reported to authorities, and regulators will scrutinize what went wrong. If a major security incident (like a successful CEO fraud wire transfer or a malware outbreak) is traced back to a spoofed email that looked like it was from your domain, one of the first questions might be: did you have measures to prevent spoofing? If the answer is “no, we never set up DMARC,” it could be seen as a lapse in basic cyber hygiene. NIS2 requires that management take cybersecurity seriously (even holding execs accountable) nis2directive.eu. So CISOs will want to cover all bases – including email auth – to demonstrate due diligence.
Potential Penalties: NIS2 will be transposed into national laws, with fines for non-compliance that can be quite hefty (potentially up to 2% of global turnover or similar, depending on the country). While a single spoofed email incident might not directly lead to a fine, regulators could determine that failing to implement common security controls is a breach of the directive’s requirements. So, neglecting email security could indirectly lead to regulatory action if it’s considered part of a pattern of non-compliance. Additionally, consider privacy regulations like GDPR – a phishing incident could result in a data breach of personal data, compounding your troubles. Using DMARC can help prevent some breaches, thus indirectly helping with GDPR (by avoiding a breach in the first place).
Other Regulatory and Industry Standards: Outside of NIS2, there are other pressures: In the U.S., government agencies were mandated by DHS to implement DMARC at p=reject back in 2018, and now insurance companies and cybersecurity ratings firms look at DMARC status as part of assessing an organization. Even PCI DSS (for payment card security) in its latest version 4.0 hints at having anti-phishing technical measures (which would logically include email authentication) blog.redsift.com.
Industry frameworks like the CIS Critical Security Controls explicitly include DMARC implementation (Control 9.5: “Implement DMARC policy and verification, starting with SPF and DKIM” cas.docs.cisecurity.org) as a recommended safeguard. If you follow ISO 27001 or NIST guidelines, while they might not spell out DMARC, they do require protecting communications and preventing impersonation, which DMARC addresses.
Even cyber insurers might start asking if you have DMARC enforced – because if you don’t, your risk of a successful phishing-related claim is higher. It’s becoming a marker of a mature security program.

Bringing it back to a business perspective: Compliance is becoming a driving factor for what used to be just best practices. The convergence of Microsoft/Google’s enforcement and laws like NIS2 is essentially sending a message: Secure your email or face consequences, be they deliverability issues or legal penalties (or both).

A lightly sarcastic interpretation: “Securing email has been on the nice-to-have list for years, but now it’s on the must-have list – not just because Microsoft said so, but because governments might fine you if you get pwned via an unsophisticated spoofing attack. Consider DMARC your new legally recommended vitamin – sure, you should’ve been taking it anyway, but now the doctor (and the EU) are really insistent.”

For a concrete example, imagine a hospital (considered essential under NIS2) that gets hit by a phishing email that looked like an internal email (spoofed their domain) asking staff to reset their VPN password, leading to a breach. If that hospital never bothered with DMARC, investigators might point out that a basic measure could have blocked the phishing email outright. Under NIS2’s requirement to have risk management and state-of-the-art security, not doing something well-known and widely adopted could be seen as negligence. On the flip side, if they had DMARC at reject and the phish came from a lookalike domain instead, that’s harder to prevent – but at least they did what they reasonably could to protect their exact domain.

In summary, failing to secure email is no longer just an IT problem; it’s a governance and compliance problem. The legal/regulatory landscape is ensuring that if the fear of spam folder wasn’t enough, the fear of fines or legal trouble will get executives on board. As a CISO or business leader, this means you can get more support (budget, prioritization) for email security projects by highlighting the compliance angle. Instead of “we’ll reduce spam and phishing,” you can say “we’ll meet Microsoft’s requirements and avoid regulatory compliance issues by doing XYZ.” That tends to get boardroom attention.

Next, let’s look specifically at the complexity EU organizations face in juggling these technical and legal requirements, and some tips to manage it without losing your sanity.

6. EU Organizations and the Complexity of Dual Compliance (Technical & Legal)

If your organization is based in the EU (or even just operates there), you might be feeling the squeeze: On one hand, your tech teams need to implement these email authentication changes to keep your communications flowing. On the other hand, your compliance and legal teams are reading through NIS2, GDPR, and possibly other regulations, making sure you check all the boxes. It can feel like navigating a minefield with both IT and legal challenges interwoven. Let’s analyze some of these complexities and how to tackle them:

Multiple Stakeholders to Satisfy: Implementing SPF/DKIM/DMARC isn’t just an IT project; it touches marketing, communications, legal, and leadership. In the EU context, you likely need to get buy-in across departments. For instance, Marketing needs to understand that they can’t just spin up a new email campaign tool without IT’s involvement (because of DMARC enforcement). Legal/Compliance needs to understand what DMARC is because it could be mentioned in security audits or regulatory filings as a control. One way to manage this is to form a cross-functional team or task force for “email security & compliance” – include IT ops, security, marketing ops, etc. The goal is to make sure everyone knows their role (e.g., if marketing wants a new SaaS sender, there’s a process to update SPF/DKIM; if IT changes something in DNS, they inform others).
Policy vs. Practice: EU entities often need documented policies for compliance. You might find yourself updating your security policies to explicitly mention email authentication. For example, a policy statement like “All outbound organizational email must be authenticated via SPF, DKIM, and protected by a DMARC policy. All new email-sending services must be approved by IT Security and configured for DMARC alignment.” This goes into your company’s security standards. It helps satisfy auditors that you have a formal stance on this (which aligns with NIS2’s requirements to have security policies and risk management processes).
Technical Challenges with Decentralized Teams: Many EU organizations, especially those spread across countries or with subsidiaries, might have disparate email systems or multiple domains. Aligning them under one DMARC policy regime can be tricky. For example, a multinational might have company.fr, company.de domains for different regions, each used by local teams. You’ll need to coordinate a unified approach – or delegate to local IT to implement under central guidance. There’s complexity in ensuring consistency (you don’t want one country’s domain to be the weak link that gets spoofed). Tools that centralize DMARC reporting across domains can be useful here, as is executive support to get all regions onboard.
Legacy Systems in Regulated Industries: Some EU industries (like utilities, manufacturing, etc.) have older systems that send emails and are hard to change. Compliance requirements won’t accept “our plant control system from 2005 can’t do DKIM” as an excuse for a security gap. The complexity is figuring out compensating controls. Maybe the workaround is to have that system send through an email gateway that can add DKIM. Or if absolutely impossible, segregate its email domain (like use a subdomain just for that system and treat it specially in DMARC policy). One might even consider exemptions internally, but be careful – from Microsoft/Google’s perspective, there’s no exemption. So you might put that legacy system’s emails in a subdomain with its own DMARC set to none so it doesn’t get blocked, but that’s a temporary band-aid.
Ensuring Continuous Compliance: NIS2 and similar laws aren’t one-time – you have to continuously comply. That means after initial implementation, you need processes to maintain SPF/DKIM/DMARC. For instance, if you change email providers or add new ones, your DNS records must be updated. One common complexity is the DNS management itself – some organizations have outsourcing or slow processes to change DNS (maybe handled by a central IT or an external provider). Ensure those processes are streamlined, because you might be updating DNS frequently as you tighten SPF includes or rotate DKIM keys. Also, consider monitoring: use a monitoring service or script to alert if any of your critical DNS records (SPF/DKIM/DMARC) change or accidentally get messed up. It’s not unheard of for a well-meaning admin to add something to SPF and accidentally break syntax, for example. That could suddenly put you out of compliance and cause email issues until fixed.
Training and Awareness: EU orgs need to train staff on cyber measures per NIS2. This is an opportunity to include a bit about email authentication in security awareness training for IT staff, and maybe even for general staff (e.g., why sometimes an email might be rejected). Also, train the helpdesk – if DMARC causes an email to be rejected, your support team might get calls like “External person X isn’t getting our emails.” The support should know to consider “Is our DMARC blocking it?” (or more likely, the external person’s DMARC blocking something). In one ironic twist, your outbound might be perfect, but if a partner domain has strict DMARC and one of your automated systems tries to forward something poorly, it might bounce. Troubleshooting email issues in the new world may require looking at authentication results.
Balancing Privacy (GDPR) Concerns: Generally, DMARC data doesn’t conflict with GDPR – aggregate reports don’t contain personal data, and even forensic reports, if you use them, should be handled carefully. But be aware: if you use an external DMARC monitoring service, you might be sending them data that includes your email headers (some of which might have personal info like sender/recipient emails in forensic reports). Make sure you have a Data Processing Agreement (DPA) with such providers if needed. This is a minor point, but in EU one has to dot the i’s. However, securing email via DMARC is actually a net positive for GDPR, because it can prevent certain types of personal data breaches (e.g., someone tricking an employee to give out data via a spoofed email).
Documentation for Audits: If you fall under NIS2, expect that auditors or regulators (or internal audit) will ask “How have you secured email?” You should be prepared to show documentation: e.g., screenshots of DNS records, policy documents, perhaps metrics like “we have DMARC coverage on 100% of domains at p=quarantine, aiming for p=reject by Q4.” If you’ve got that cross-functional team, record their meeting minutes and plans – it demonstrates a proactive approach. The complexity is turning a technical control into an audit-ready item. A nice approach is to align it with an existing framework: e.g., map it to CIS Control 9.5 (which we cited) cas.docs.cisecurity.org or ISO 27002 control about protecting against spam/phishing. Then you can show you meet that via these implementations.

It might feel like a lot, but think of it this way: Email authentication is one of those rare security measures that has immediate tangible benefits (better deliverability, less phishing) and also helps check compliance boxes. Many security projects feel like insurance; this one feels like insurance and performance enhancement. Use that to your advantage in justifying the effort.

One complexity we must note: Not every email scenario will neatly fit DMARC’s rules. Some valid use cases (like certain types of mailing lists, or when a partner sends on your behalf in a way that’s tough to align) may present gray areas. You may need to make some tough choices:

For example, if a particular workflow absolutely cannot be made DMARC-compliant, do you carve out an exception? (E.g., allow that subdomain to stay at p=none while others go to p=reject.) But then, will Microsoft/Google treat that subdomain’s mails as suspect? Possibly. They might specifically be focusing on root domains used for bulk. If your main domain is compliant but a tiny subdomain isn’t, you might fly under the radar. But it’s a risk.
Alternatively, you might retire or replace that problematic system. This is where you escalate to management: “We have System X that can’t meet the security requirement. We either upgrade it or decommission it, because otherwise our emails to Outlook/Gmail could be junked and we’d be non-compliant with policies.” This can trigger investment in modernization (silver lining!).

EU-based CISOs have to juggle technical fixes and ensure everything is by the book. It’s a bit of extra work, but on the bright side, meeting Microsoft’s requirements by May 2025 inherently helps meet NIS2’s late-2024/2025 timeline for having stronger controls. You can essentially kill two birds with one stone – and you can report up to your board and regulators: “We have implemented advanced email security controls (SPF/DKIM/DMARC at enforcement) in line with industry best practices and emerging regulations.” That sounds impressive (because it is).

Finally, let’s lighten it up a bit and use a couple of analogies or examples to wrap up the technical parts, then we’ll conclude with next steps and references.

7. Real-World Analogies and Examples to Drive the Point Home

We’ve covered a lot of ground. To make sure the concepts are clear even to a non-technical business audience, here are a few analogies and real-world parallels:

The VIP Club and Bouncer Analogy: Picture your email domain as an exclusive club. SPF is the bouncer with the guest list (only allows entry to those on the list – i.e., servers you approved) learn.microsoft.com. DKIM is like each guest having a special badge or hologram sticker that proves their invite is genuine and hasn’t been tampered with en route. DMARC is the club manager’s policy that says “if someone shows up without an invite or a fake invite, here’s what to do – deny entry and report it to me.” Under the new rules, Gmail/Outlook are essentially telling club managers (domain owners): “No more leniency – if someone doesn’t have the proper invite and badge (SPF/DKIM), we’re not letting them in, period.” If you’re the club owner who didn’t set up a guest list or give out authentic badges, lots of legitimate guests might get turned away and fake ones might have snuck in. Not good for business or security!
Driver’s License Analogy: Think of an email like a person trying to get on a flight. SPF is like checking that their ticket was issued by a legitimate agent (and not a forgery), DKIM is like checking that their passport isn’t fake and the photo hasn’t been swapped, and DMARC is the policy that says “deny boarding if either the ticket or passport fails validation.” What Microsoft, Google, et al. are doing is akin to the TSA saying “we will now enforce that rule strictly for anyone with more than 5,000 passengers (emails) a day.” If you as an airline (sender) haven’t ensured your passengers have legit tickets and passports, they’re going nowhere.
Real Example – Stop Spoofing: A few years back, domains like paypal.com and irs.gov were commonly spoofed in phishing. DMARC has helped many big brands drastically cut down on exact-domain spoofing. For instance, the U.S. IRS implemented DMARC, and phishing emails pretending to be the IRS (from their real domain) essentially stopped reaching users – scammers had to use lookalike domains instead. That’s a win. Now imagine this on a broad scale: if all banks, all healthcare orgs, etc., have DMARC at reject, cybercriminals can’t use those exact domains to fool people. They’ll try other tricks, but one door is closed. The more organizations that do this, the narrower the scammers’ options. Microsoft’s and Google’s efforts are forcing this positive change. A CISO can frame DMARC enforcement internally not just as compliance, but as brand protection: “We don’t want someone sending emails as @ourcompany.com to our clients and hurting our reputation or causing fraud. DMARC reject ensures that if they try, those emails won’t get through on major email services.” It’s like putting a global “do not impersonate” shield on your domain.
Analogy – Locks on Doors: SPF, DKIM, DMARC are like putting good locks on your doors and instructions to the security guard. For years, email was like a house with the door left kinda ajar – if someone walked in saying they’re the plumber (even if they weren’t), the old security guard (mail provider) might shrug and let them through to your living room (inbox). Now, the security guards have been told “check IDs and work orders (SPF/DKIM) for any plumber that comes in, and if they don’t check out, follow the homeowner’s instructions – likely, don’t let them in (DMARC policy).” Homeowners (domain owners) who never gave any instructions before (no DMARC) are now quickly pasting a note on the door saying “if not legit, at least send them around to the back (junk) or away entirely.” The result: fewer uninvited “guests” in your house, and more assurance that those who are in are supposed to be there.
Statistic to illustrate readiness: A recent study found that as of end of 2023, about one-third of large organizations worldwide would fail the new DMARC requirements if they were enforced immediately blog.redsift.com. That’s a lot – and likely includes some companies who think their email is fine. So if you’re reading this and realizing your company is behind, you’re not alone – but the tide is turning fast. By taking action now, you can leapfrog into the more prepared two-thirds and avoid the scramble. It’s much better to fix it on your terms than to have, say, Microsoft flip the switch and suddenly your customer emails tank. As the saying goes, “Fix the roof while the sun is shining.”
Humor in Non-compliance: If you need to add a dash of humor in a presentation to your execs: “So, what happens if we do nothing? Well, our marketing emails take a lovely trip to Spamland, our partners think we’ve ghosted them, and our helpdesk gets to answer calls like ‘why aren’t you responding to me’ all day. Then at the next board meeting, we can explain how we missed out on sales because we couldn’t be bothered to add text records to DNS. Sounds fun, right? No? Okay, let’s do this project.” Sometimes a little dramatic flair drives the point home that this is serious, albeit with a chuckle.

With these examples in mind, the message is clear: Email authentication is both important and achievable, and the new requirements simply put a timeline and impetus on something that ultimately benefits your organization.

Before we close out, let’s outline a quick structured plan (because CISOs love plans) you might follow to implement all this, and then we’ll provide references for further reading:

Action Plan Outline:

Discover – Inventory all domains and subdomains that send email for your organization. Inventory all third-party services and internal systems that send email. Use DMARC reports (by deploying p=none policies ASAP) to aid in this discovery.
Implement – Configure SPF for each domain (and subdomain as needed). Implement DKIM on all email-sending platforms (generate keys and publish DNS records). Set up DMARC records at p=none with reporting addresses to gather data.
Assess – Review DMARC aggregate reports for at least 1-2 months. Identify any sources that are failing. Fix those (adjust SPF, DKIM config, etc.). Communicate with any third-parties who are failing and get them to update settings.
Enforce – Gradually move DMARC policies to p=quarantine for a safe period (maybe another month or two) once you believe all legitimate mail is aligned. Monitor for any unexpected issues (legitimate mail going to junk).
Lockdown – Move policies to p=reject for full enforcement. This should ideally happen before Microsoft’s final cutoff when they start rejecting (which is TBD, but presumably within a year after May 2025) techcommunity.microsoft.com. Gmail/Yahoo may not outright reject if you’re at p=none, but they could still spam-folder – so p=reject ultimately maximizes your deliverability for authentic mail (and blocks fakes).
Maintain – Treat any addition of a new email sender as a change control: update SPF/DKIM, and test. Keep an eye on DMARC reports continuously or at least periodically. Renew DKIM keys every so often (rotate keys perhaps annually for good hygiene).
Document & Train – Ensure your security policy documents reflect these controls. Train relevant staff (IT, marketing, etc.) about the do’s and don’ts. Be ready to demonstrate compliance to auditors with records of what you’ve set up.
Monitor Ecosystem – Stay tuned to updates. For instance, if tomorrow another major provider (say, a European ISP) announces similar requirements, you’ll want to know. But if you’ve done the work, you’re largely future-proofed. Also watch for updates on when Microsoft will move from spam to full rejection (they promised to announce later) techcommunity.microsoft.com.

Alright, as the (sarcastic) saying goes: “That sounds like a lot of work just to ensure our emails actually arrive, but welcome to 2025.” The upside is once this is done, you can rest a bit easier that one big piece of the phish-fighting puzzle is in place, and your organization won’t be caught off guard by these changes.

Let’s wrap up.

8. Conclusion – Embrace the Change (Your Email and Your CISO Will Thank You)

Email has often been dubbed the “wild west” of the internet – too long it’s been possible to send an email claiming to be anyone, from anywhere. The moves by Microsoft, Google, Yahoo, and Apple are finally taming that wild west by enforcing law and order (or at least ID checks at the saloon door). For high-volume senders, the message is clear: authenticate or lose access to the inbox. While the tone of this guide has been lightly sarcastic to keep things lively (after all, who hasn’t sat through dull meetings about DNS records?), the importance of the topic is very real.

If you’re a CISO or IT leader, use this moment to champion a worthwhile security enhancement. It’s not just about appeasing Microsoft or complying with NIS2 – it’s about protecting your brand, your customers, and your bottom line from the very tangible threat of phishing and spoofing. And if you’re a business executive, realize that this “technical tweak” has broad implications: marketing ROI, customer trust, and even legal compliance hinge on getting it right. This is a rare case where doing the secure thing and doing the business-smart thing are one and the same.

So deploy those SPF records, rotate those DKIM keys, and push those DMARC policies to enforcement. Then you can enjoy the benefits: higher confidence that when your domain is in an email “From” address, it’s truly you, and that your emails reach recipients as intended. As Microsoft’s team said, “embracing better authentication and hygiene not only benefits your deliverability but also helps protect the entire email ecosystem” techcommunity.microsoft.com.

In a year’s time, when your organization’s emails sail smoothly into inboxes while others scramble asking “why are our emails going to spam?”, you’ll be the unsung hero who saw the writing on the wall and acted. And maybe, just maybe, you can finally reduce those phishing incident response meetings because the spoofed emails aren’t getting through in the first place. Wouldn’t that be nice?

Now, to equip you with further reading and resources, here’s a list of references including official announcements, documentation, and best practice guides that underpin the points we’ve discussed. Use these to dig deeper or to support your case when getting buy-in.

9. References and Further Reading

Microsoft Tech Community Blog – “Strengthening Email Ecosystem: Outlook’s New Requirements for High-Volume Senders” (April 2025) – Official announcement of the new requirements for Outlook.com (Hotmail/Live) domains, including the 5,000 emails/day threshold and enforcement timeline.

techcommunity.microsoft.com

Proofpoint Blog – “Google and Yahoo Set New Email Authentication Requirements” (Oct 2023) – Summary of Gmail and Yahoo’s policies effective Feb 2024, requiring SPF, DKIM, DMARC for bulk senders (5k+ emails/day), and highlighting Apple’s similar best practice guidance.

proofpoint.com

Google Support – Bulk Sender Guidelines – Detailed guidelines from Google on sending bulk email, including authentication and spam rate requirements. (Google’s reference for the Feb 2024 changes.)

proofpoint.com

Apple Support – iCloud Mail Postmaster Info – Apple’s best practices for senders, stating the need for SPF, DKIM and that sending domains “must” publish a DMARC policy to not be considered junk by iCloud Mail.

support.apple.com

Red Sift Blog – “Microsoft announces new email requirements for bulk senders” (April 2025) – Analysis of Microsoft’s move, with emphasis on aligning with Google/Yahoo and urging senders to check compliance (includes a free checker tool). Reinforces timeline and importance of DMARC.

blog.redsift.com

Red Sift (Email Security Guide) – DMARC and NIS2 – Explainer on how a DMARC reject policy aligns with NIS2 Directive requirements (security by design, risk management, supply chain security, etc.), arguing that not having DMARC could weaken NIS2 compliance.

redsift.com

CIS Critical Security Controls v8 – Control 9.5 (Implement DMARC) – Security framework control explicitly recommending SPF, DKIM, and DMARC implementation to combat email spoofing.

cas.docs.cisecurity.org

CISA Guidance – Phishing Best Practices (Oct 2023) – U.S. Cybersecurity and Infrastructure Security Agency guidance (co-authored with FBI/NSA) recommending organizations implement SPF, DKIM, and DMARC at p=reject to combat phishing.

blog.redsift.com

Global Cyber Alliance – DMARC Setup Guide – Practical step-by-step guide to implementing DMARC (and SPF/DKIM) for organizations, useful for technical teams setting up records. (GCA, globalcyberalliance.org DMARC Guide)
M3AAWG Best Practices for Senders – Industry best practices from the Messaging Malware Mobile Anti-Abuse Working Group, covering bulk sending behavior (list management, unsubscribe) and authentication – aligns with what Gmail/Microsoft are asking.

support.apple.com

European Union NIS2 Directive Text – Directive (EU) 2022/2555 full text for reference. While it’s not light reading, relevant sections (e.g., Article 21 on security measures) underscore the need for measures like email security. (EU NIS2 Directive, Article 21, 23 on security requirements – eur-lex.europa.eu)
Stats on DMARC Adoption – Red Sift “2024: Year of DMARC as Business Imperative” report, which noted ~33% of large orgs would fail new requirements as of Dec 2023, highlighting the need to improve

blog.redsift.com

. (Helpful for building the business case with data.)

Microsoft Learn – Email Authentication in Microsoft 365 – Official documentation explaining SPF, DKIM, DMARC and ARC in the context of Microsoft 365, including how to set them up in that environment.

learn.microsoft.com

InboxAlly Blog – “SPF, DKIM, DMARC explained [Infographic]” – A user-friendly explanation (with infographic) of the three protocols and how they work together, useful for educating non-technical stakeholders.

By following the guidance in this article and leveraging the resources above, organizations can navigate the new email authentication mandates with confidence. It’s time to lock down your email channels – your users, your customers, and yes, even your friendly neighborhood regulators, will thank you. Good luck, and happy authenticating!

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venerdì 11 luglio 2025