Hi All, We're seeing instances of emails being rejected by Microsoft with DKIM errors, and I have no idea why. It's happening to maybe 1% of the email we send to Microsoft properties (outlook.com, hotmail.com, live.com, etc). The error we get is:
550 5.7.515 Access denied, sending domain GROUPS.IO doesn't meet the required authentication level. The sender's domain in the 5322.From address doesn't meet the authentication requirements defined for the sender. To learn how to fix this see: https://go.microsoft.com/fwlink/p/?linkid=2319303 Spf= Pass , Dkim= Fail , DMARC= Pass These are email group messages. We re-write the From line for all of them, so they all have the @groups.io domain. For a given list message, if it fails for one Microsoft recipient, it fails for all of them. I dump out these emails and run two different DKIM signature check programs on them, and they pass. Does anyone have any suggestions for things I should check? Thanks, Mark
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