No SMTP servers were available for domain – repeated delivery failures

[jishanalibd]

Describe the bug

I am experiencing a persistent issue with Postal where emails fail to deliver with the error message:

No SMTP servers were available for [recipient-domain]. Tried [mx-record].
execution expired

This causes soft fails and emails being held. Example from logs:

No SMTP servers were available for pacificbluejeans.com. Tried pacificbluejeans-com.mail.protection.outlook.com.
execution expired
Support Ref: XCG5OF48

Please advise on further troubleshooting or fixes.

[jishanalibd]

root@smtp:/opt/postal# telnet pacificbluejeans-com.mail.protection.outlook.com 25
Trying 52.101.157.80...
Connected to pacificbluejeans-com.mail.protection.outlook.com.
Escape character is '^]'.
220 OSA0EPF000000C7.mail.protection.outlook.com Microsoft ESMTP MAIL Service ready at Thu, 18 Sep 2025 06:48:27 +0000 [08DDF46218B8950F]

[jishanalibd]

No SMTP servers were available for multirbl.valli.org. Tried mx01.valli.org.
execution expired
Support Ref: P8KTAB7C

---

No SMTP servers were available for cuestablanca.com.ar. Tried aspmx.l.google.com, alt1.aspmx.l.google.com, alt2.aspmx.l.google.com, aspmx3.googlemail.com, and aspmx2.googlemail.com.
execution expired
Support Ref: ZWC6WTS6

[willpower232]

Have you confirmed with your server provider that you are able to send emails from your server?

[jishanalibd]

Yes, even I able to send mail from same instance but most of not.

Message for [email protected] accepted by 52.101.157.80:25 (pacificbluejeans-com.mail.protection.outlook.com)

250 2.6.0 <[email protected]> [InternalId=30910879635258, Hostname=TY0PR04MB6205.apcprd04.prod.outlook.com] 24664 bytes in 0.326, 73.875 KB/sec Queued mail for delivery
Time: 1.51s
Support Ref: 8RUJ8BGR

[willpower232]

if your server provider says they aren't blocking you then presumably microsoft or google is intermittently blocking you so not much you can do, have you checked mxtoolbox.com?

[jishanalibd]

Yes, here's mxtoolbox.com report.

presumably microsoft or google is intermittently blocking you

What about other host? I try to send to mail-tester.com, multirbl.valli.org but unable sent cause No SMTP servers were available for domain , If I ask recipients to confirm that they blocking me or not, what to ask?

[craigrileyuk]

We're getting the same issue with a few domains on our Postal server as well.

1. virginmedia.co.uk
2. ntlworld.com
3. mailcluster.zen.co.uk

January 05, 2026 13:31
Soft fail

No SMTP servers were available for ntlworld.com. Tried mxin5.virginmedia.com and mxin10.virginmedia.com.

end of file reached

Support Ref: 7NJO18GV

All other email sends perfectly, so there's obviously something different about how these domains handle email. We've tried the same addresses through a non-Postal email and it works.