[German]I'm posting an observation from a German blog reader that relates to Microsoft's Exchange Online. The reader is confronted with the problem of complaints from business partners about emails that have not "arrived". There is a suspicion that Exchange Online may be manipulating the email senders.
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A German blog reader had already contacted me by email on December 13, 2024 and wrote under the subject "Microsoft Exchange Online changed sender?" that he was currently receiving more and more complaints in the company that emails were not arriving at the partner.
The IT department then investigated this problem. After research, they found out, writes the reader, that an MS Cloud IP always appears as the sender in the emails in question.
However, the company's email servers are only operated on-premises. According to the reader, all logs show that the mail left the company's email system and was successfully submitted to Exchange Online.
As the company has set up a strict SPF policy, the mail is discarded as SPAM, the reader states. If someone "is already in the cloud at MS and the communication is from Microsoft to Microsoft (Exchange Online mailboxes), it doesn't matter, as the Microsoft IPs are in the SPF records.
The reader notes that the SPF policy could now be softened until Microsoft has fixed this. But then blocking emails via blacklisting makes no sense either, writes the reader, explaining that more and more Microsoft IP addresses are ending up in these blacklists. The reader asks: "Are we the only ones observing this?"
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On Facebook there was the following comment "a spontaneous guess: when setting up the EXO connector, I forgot to check the 'Keep header' box." On BlueSky, Frank Carius also gave the hint "So that would be new. But there is one case: the sender is at the destination as a contact and the mail arrives via an inprwm connection." The issue is still being clarified.
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