We’re in the DOD space and have been doing email with trusted customers for years and just last week we started getting our emails into their domains getting put in the Junk folders. Our DMARC, DKIM and SPF look good and has been working for a long time until last week. Does anyone know of any changes that Microsoft may have made last week to tighten their inbound email requirements. The one header retrieved from a customer showed an inbound MS service of itar.protection.office365.us so we expect them to be pretty tight to protect ITAR.
Hi John and welcome to the forums.
Microsoft updates are frequent, and most often not divulged to the public. No major change announced on their part lines up with your timeline. Moreover, several technologies could be the culprit here. To name a few:
- Spam heuristics
- Bayesian networks
- Domain reputation
- Connection filters
- Recipient blocklists/custom filters
It might be worthwhile to understand if they are the only recipient with which you are facing this issue, or is it the Microsoft community at large. Microsoft add a fair bit of information in the headers to understand which security module ends up causing a spam verdict, so it may be worthwhile working with the recipient in an attempt to review a sample.
If you are facing issues across all recipients on Microsoft products, it might be best to follow a false positive submission process.
I hope this helps and good luck!
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