How to meet Microsoft sender address rules

It’s official: email best practices are no longer best — they’re required. Here’s why... Microsoft recently announced new bulk sender requirements that mirror the ones Google and Yahoo rolled out last year. And they aren’t just doing this for fun, promise. They’re doing it because too many senders ignored best practices when they were optional. So, now they’re mandatory. ¯\_(ツ)_/¯ Starting May 5th, if you’re sending more than 5,000 emails a day and not following the rules, Microsoft’s going to start rejecting your mail. Not junking it. Rejecting it. And I wanna be clear here: this isn’t coming out of nowhere. The writing’s been on the wall for a while... and mail has been silently filtered away from the inbox all this time. Now it's just that the rules aren't written in invisible ink! So, what are these rules I speak of? 💌 Authentication (SPF, DKIM, DMARC) Yes, we’re still talkin’ about this… get used to it. Microsoft wants the same setup Google and Yahoo asked for. If your domains aren’t properly authenticated and aligned, your deliverability will suffer. 💌 Valid “From” and “Reply-To” Addresses Microsoft wants to make sure that when someone replies to your message, there’s someone on the other end. No more sending from a “noreply@brand.com” black hole. 💌 One-Click Unsubscribe (RFC 8058) They’re cracking down on bad unsubscribe flows. Make it easy. No weird hoops or loops or “oops, we need 10 days to process your request.” Just a simple unsubscribe option that actually works. If you’re already sending it right (ahem, compliant with Google and Yahoo’s requirements), this is mostly a “cool, cool, carry on” moment. But you’ll need a whole lotta margaritas and tacos to overcome your sorrow if you’ve been dragging your feet. May 5th (ahem, cinco de mayo!) is not the day to find out Microsoft doesn’t play. What happens if you’re not ready? If you need help figuring out where you stand, here are a few fast checks: ✅ SPF, DKIM, and DMARC passing in headers? ✅ “Reply-To” address monitored and functioning? ✅ One-click unsubscribe live and working? ✅ Lists clean and bounce/spam complaint rates under control? If not, now’s the time to fix it. Not next week. Not next quarter. Now. TLDR: if you’re not sending responsibly, you’re not sending at all. Because come Monday — yes, THIS Monday — non-compliant mail will be rejected at the door. No inbox. No spam folder. Just blocked. So, get it together, you (not so) filthy animals! LinkedIn says I’m outta characters, but if you need tool recommendations or a second set of eyes on your setup, I'm happy to help. Reach out, email scout. 💌

If you’re still sending email from an onmicrosoft.com address, Microsoft is tightening the rules. This matters because your messages could start getting throttled or blocked, which means invoices, password resets, and customer updates might never arrive. Microsoft’s goal is to stop spammers who spin up fresh tenants and abuse the shared onmicrosoft.com domain. But the side effect is real organizations will see lower deliverability and limits on bulk or automated sends until they move to a proper, verified domain. What’s changing? Microsoft is putting sending limits and stricter checks on any email that leaves an onmicrosoft.com address. Because it’s a shared domain used by millions, one bad actor can hurt the reputation for everyone. The fix is simple but urgent: switch to your own branded domain and set up modern email authentication (SPF, DKIM, and DMARC). That tells receiving mail systems, “Yes, this is really us,” and helps keep your mail out of spam and off block lists. What should you do now? Audit where onmicrosoft.com shows up—service accounts, no-reply inboxes, ticketing tools, scanners, CRM alerts, and scripts. Register or connect your custom domain, add the DNS records, and rotate apps and automations over to the new addresses. Test mail flow, watch for bounce backs, and update address books, forms, and templates. Train your team so they know which sender addresses are approved going forward. A little cleanup today will save a lot of missed messages tomorrow. #Microsoft365 #EmailSecurity #ITAdmin #ChangeYourPassword Follow me for regular updates on Microsoft 365 changes, security tips, and clean-up checklists that keep your org’s email flowing.

Microsoft dropped their new rules today for high-volume senders... They are expected to come into enforcement in just over 30 days. The main update. Any messages for high-volume senders (more than 5K per day) that don't pass SPF, DKIM and DMARC will: a) Get routed through to the junk/spam folder. b) Start to be completely blocked if this isn't resolved. This might ring a bell because Google and Yahoo did something similar in late 2023. So, if you pass DKIM, SPF, and DMARC -- What's the big deal? These guidelines typically signal additional tightening of spam filtering in general, so I wouldn't be surprised if you see deliverability issues start to increase. Some of the recommended guidance from Microsoft includes: 1. Clean your lists: Ideally, on a monthly basis (Allegrow has your back). 2. Clear Unsubscribe Options: Provide visible, functional opt-out mechanisms, especially for marketing emails. 3. Valid Sender Addresses: Use legitimate "From" or "Reply-To" addresses that match your sending domain and can receive responses. Interestingly, Outlook specifically mentioned that they reserve the right to take NEGATIVE ACTION, particularly against senders who breach email hygiene or authentication standards. So, bounces increase the chances of your emails being flagged for filtering + blocking. Outlook has stated this applies to ‘Outlook.com - our consumer service, which is supporting hotmail.com live.com’, probably because of the backlash Google support received when they announced similar policies for workspace users. Although this applies specifically for messages sent to those types of inboxes (at the moment), it does apply to senders FROM ANY email provider or service. The first comment will provide the full post from MS.