That is an office 365 free trial account. There is some massive abuse of these going on over a period of time. However there is also a ton of legitimate traffic.
--srs ________________________________ From: mailop <mailop-boun...@mailop.org> on behalf of MRob via mailop <mailop@mailop.org> Sent: Wednesday, November 9, 2022 5:17:09 AM To: mailop@mailop.org <mailop@mailop.org> Subject: [mailop] Try to understand *.onmicrosoft.com Is envelope sender user@<anything>.onmicrosoft.com normal in non-spam mail? Is it how all microsoft mail comes through? Or is it usually spam from badly configured domain? Should <anything> part *always* match sender domain in FROM header? On the other hand, if mail come from microsoft server *not* through "onmicrosoft.com" is that negative sign? Thank you. _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
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