On 2025-12-10 at 17:35 +0100, Marco Moock wrote: > Hello! > > Today I posted to a mailing list (not hosted at MS) and that post got > delivered to the subscribers (myself included). > (...) > ########### > Delivery has failed to these recipients in Microsoft Teams: > [email protected]<[email protected]> > We couldn't deliver this message to Teams, because it was flagged by > anti spam policies. > > Diagnostic info for admins: > messageId: > < > 4887a27fc84244efa8cb0fbd68aaa...@bn0pr10mb4982.namprd10.prod.outlook.com > >, > serverRequestId: 50438e9a-b6a6-45ac-94d2-f064cf9ff8d3, > clientRequestId:
Their gateway seem to be doing something quite weird. Your email to oss-security was delivered with a MAIL FROM: < oss-security-return-<id>-<local-part>=<domain-part>@lists.openwall.com> From: Marco Moock <[email protected]> Reply-To: [email protected] Message-ID: <[email protected]> They seem to be reinjecting it, with a new message-id, placing the From: as sender and treating the To: as a chat room. To which they then apply an antspam check and end up sending a bounce to an innocent part. It might be that the customer has a script manually converting received emails into team messages, and not Microsoft. Either way, placing you into the MAIL FROM: for receiving error messages when they fail to send to their teams chatroom is wrong. _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
