0

I run a postfix mail server. It's been up for a while, and works perfectly in most cases. MXToolbox reports no errors, my domain isn't blacklisted, and Gmail addresses can interact with my server perfectly well.

However, it seems that microsoft doesn't want to play nice. A few people have sent me mail from microsoft services (either microsoft.com or a custom domain managed by Outlook/365), and they get a "mail undeliverable" response. The mail never reaches my server--it gets lost somewhere inside Microsoft's infrastructure.

I got my hands on one of these responses, and it seems that Microsoft mail servers resolve my domain to 0.0.0.0. Possibly a whitelist?

Is there anything I can do to fix this problem? I'd very much like to receive email from accounts managed by Microsoft.

Additional information:

Here's the bounced response senders get:

8/2/2022 11:25:17 PM - Server at CH2PR21MB1397.namprd21.prod.outlook.com returned '550 5.4.312 Message expired, DNS query failed(ErrorRetry)'
8/2/2022 11:15:17 PM - Server at mydomain.com (0.0.0.0) returned '450 4.4.312 DNS query failed [Message=ErrorRetry] [LastAttemptedServerName=mydomain.com] [CB1PEPF0000204A.namprd00.prod.outlook.com](ErrorRetry)'

MS internal servers are resolving my domain to 0.0.0.0.

My DNS configuration is fairly simple, with a single MX record on mydomain.com that points to mail.mydomain.com, as well as the usual DMARC and DKIM records. I'm fairly sure nothing is wrong with my DNS config, I've tested it with a few provides and they all work perfectly. Although, anything is possible.

Lurata
  • 1
  • 1
  • 1
    We need info about yor dns configuration, dig MX yourdomain at least – gapsf Aug 02 '22 at 20:38
  • 1
    "got my hands on one of these responses" - [*show it*](https://serverfault.com/posts/1107226/edit). There is at least one, depending on Microsoft-internal forwarding possibly multiple hints about the nature of the problem in those notifications. – anx Aug 03 '22 at 03:24
  • 1
    "DNS query failed"? Please use tools like [DNSviz](https://dnsviz.net/) and [zonemaster](https://zonemaster.net/) to identify common problems. Usually though, questions involving DNS get better answers if you just publish the name in question - if you expect it to be visible to Microsoft I guess it is public anyway. – anx Aug 03 '22 at 04:59

0 Answers0