Showing posts with the label microsoft

Lukas Lunow: Why Does Microsoft Trash My Emails?

If you're living in the land of Salesforce Marketing Cloud and struggling when it comes to getting your emails reliably delivered to Microsoft inboxes, then this guide is for you. A longtime Salesforce consultant (and previously an expert solutions consultant for the Salesforce mothership), Lukas Lunow has pulled together this excellent reference guide on Microsoft deliverability woes,…
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SNDS and JMRP in transition

Microsoft's sender reputation data portal ( Smart Network Data Services , or SNDS) and their ISP feedback loop mechanism (Junk Mail Reporting Program, or JMRP), are undergoing a transition. The SNDS website relaunched in June, 2026, with updated access controls and some ch…

Troubleshooting 4 different types of Microsoft DKIM rejections

If your attempts to send email to Microsoft-hosted inboxes are bouncing back intermittently with authentication-related rejections; specifically highlighting that DKIM is failing, when you know you’ve got DKIM authentication correctly implemented: what do you do now? The actual…

Microsoft DKIM Failures? Check for double headers

Another day, another issue with DKIM signatures. As has happened before, and as will likely happen again, everything looks great for an email message at mailbox provider A, but gets rejected or otherwise runs into trouble at mailbox provider B. If you’ve been in email deliverab…

Weird DKIM failures? Check your header lengths

If you’re running into issues with DKIM signatures failing when sending to Microsoft domains, but working fine elsewhere, one thing to check is that your various email headers aren’t too long or wrapped improperly. Postmark’s blog post from January touches on this very issue ; …

Microsoft rate limiting issues?

Seeing rate limiting deferrals at Microsoft OLC (Outlook Consumer/Hotmail) domains ? Specifically with this error message: 451 4.7.650 The mail server [IP Address] has been temporarily rate limited due to IP reputation. For e-mail delivery information, see https://aka.ms/postma…

Microsoft SNDS: It's alive!

Look what I just found in my email. It's an email from staff AT hotmail.com: You are receiving this message because your sender IPs are enrolled in the Junk Mail Reporting Program (JMRP). We are modernizing JMRP by rebuilding the service on a new platform. Going forward, pr…

Wait, what is Microsoft SNDS? (for 2026)

Every time I post about changes to Microsoft SNDS, somebody always asks, “What, what is Microsoft SNDS? How do I use it?” And so, to be proactive this time around, allow me to link to this wonderful introductory overview and explainer from fellow deliverability expert, Iterable…

January 2026 Microsoft SNDS Updates (So far)

If you use Microsoft’s SNDS (Smart Network Data Services) online reputation portal to monitor for deliverability and reputation indicators for mail you’re sending to Microsoft OLC (Outlook Consumer, aka Hotmail/Outlook.com) mailboxes, you might have noticed this already. Clear…

Microsoft is pulling support for inline SVG images

Microsoft is removing support for inline SVG images in Outlook for Web and Outlook for Windows. This started rolling out in early September and should hit everyone by mid October. BleepingComputer has the full writeup here . Email designers and coders, be aware. Though, I rathe…

SPF fail, DKIM pass, DMARC pass: A confusing Microsoft rejection

Here's a confusing rejection that an email sender asked me about the other day. It's a Microsoft OLC (Outlook Consumer, aka Hotmail or Outlook.com) rejection, authentication related, saying that the message in question doesn't pass authentication checks: 550 5.7.515…

Microsoft SNDS: Minor changes

Microsoft's SNDS (aka their Smart Network Data Services email reputation data portal) has recently undergone some minor updates that might impact your use of the platform, depending on how you utilize it. The CSS and design seem to have been updated just a tiny bit, making…

Microsoft to limit sending from onmicrosoft.com

When you spin up a Microsoft 365 environment to handle email for your corporate or other organization, the system assigns you a default email domain that looks like something.onmicrosoft.com. This subdomain (with your Microsoft environment tenant name in it) is meant as a plac…

Steve Atkins: Short TTLs Causing Delivery Issues?

Some senders are reporting inconsistent, hard-to-pin-down authenticated-related delivery failures when sending to Microsoft domains. Here's a theory about on thing that might be related: overly short DNS TTL (time-to-live) settings on SPF, DKIM, or CNAME records might be co…

Microsoft says: Too Many Connections

Here's one I hadn't seen before. A sender was hitting this deferral when trying to deliver mail to Microsoft (Hotmail/Outlook.com) domains: smtp;451 4.7.652 The mail server [x.x.x.x] has exceeded the maximum number of connections. (S3115) What stands out here is that Mi…

Webinar alert: New Microsoft Sender Requirements

Microsoft recently joined the "top four" mailbox providers (aka "MAGY," Microsoft, Apple, Google, and Yahoo) with updated authentication and email hygiene standards for email senders . If you send more than the bare minimum number of email messages per day, …

FAQ: Four Common Email Authentication Failure Scenarios

In my latest Valimail Ask Al Video , I walk through four specific email authentication failure scenarios, things that could trip you up when sending email to Microsoft recipients, especially now that they’ve “ gotten on the bus ,” having announced new Yahoogle-comparable bulk s…

Microsoft: P2 Sender Address Compliance

In light of all the chatter around the new Microsoft sender requirements , I’ve started to capture and catalog the various questions I’m getting from senders as they work toward ensuring that they fully comply with this updated guidance. The one question I’ve received the most …

Cinco de Microsoft is here: What you need to know

What the heck is Cinco De Microsoft? Why, today is. Monday, May 5, 2025, the date when, as announced by Microsoft , non-compliant bulk email messages sent to Microsoft consumer mailboxes (hotmail.com, live.com, outlook.com, etc.) will now be rejected. If you’re sending emails, …

New Microsoft Sender Requirements: Link Roundup

By now, you've probably heard: Microsoft has officially joined the club. Following in the footsteps of Google and Yahoo, Microsoft has announced new requirements for high-volume and bulk email senders targeting their consumer domains (the biggest ones being Outlook.com, Hot…