EMail server gets blocked by Microsoft

yasuo at yasuo at
Tue Apr 27 14:20:33 UTC 2021

Hi Dominuque,

If you mean "Microsoft 365" mail servers, your mail server is quite possibly listed frequently on Spamhaus' blocklists.

Check back with Spamhaus on your reputation to find out what you can do.

跡部 靖夫 (ATOBE, Yasuo)
yasuo at

-----Original Message-----
From: NANOG < at> On Behalf Of Dominque Roux
Sent: Tuesday, April 27, 2021 4:36 PM
To: nanog at
Subject: EMail server gets blocked by Microsoft

Hi All,

is there anyone out there who has some experience with the blocking mechanism of Microsofts mail server? We're running a mail server at our company which ends up on their blacklist from time to time and we're wondering if there are some steps we could take in order to prevent this.


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