Hi Dominuque, If you mean "Microsoft 365" mail servers, your mail server is quite possibly listed frequently on Spamhaus' blocklists. https://www.spamhaus.org/
Check back with Spamhaus on your reputation to find out what you can do. Cheers, 跡部 靖夫 (ATOBE, Yasuo) ya...@atobe.com -----Original Message----- From: NANOG <nanog-bounces+yasuo=atobe....@nanog.org> On Behalf Of Dominque Roux Sent: Tuesday, April 27, 2021 4:36 PM To: nanog@nanog.org 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. Cheers, Dominique
