Issue Mail delivery deferred (4.4.2 delivery temporarily suspended)

[iainh]

Server operating system version

AlmaLinux 9.5 (Teal Serval)

Plesk version and microupdate number

Plesk Obsidian 18.0.68 Update #2 Web Host Edition

Mail stopped being delivered on our Plesk server in the early hours of this morning with:

postfix/error[3062827]: 8553CC0B0A71: to=<[email protected]>, relay=none, delay=455, delays=455/0.05/0/0, dsn=4.4.2, status=deferred (delivery temporarily suspended: lost connection with 127.0.0.1[127.0.0.1] while receiving the initial server greeting)

Looking through KB articles, I have...

1. Restarted Dovecot and Postfix milter and SMTP via Tools & Settings > Services Management and requeued all mail ... failed
2. Restarting amavisd and postfix and requeuing all deferred emails as per Emails are not sent: conversation with 127.0.0.1[127.0.0.1] timed out while receiving the initial server greeting ... failed
3. Tried plesk repair mail -y and restarted Postfix and requed mail as per Unable to send email in Plesk: mail transport unavailable ... failed
4. Restarted the entire server and requed mail ... failed
5. Checked there have been no auto updates overnight (last was Fri 11-Apr)
6. Plesk Email security is not installed (although should be!)
7. There is no ClamAV
8. SpamAssassin isn't installed ... and should be (it's a new box after having an enforced rapid migration and clearly things were missed!)
9. Greylisting was not enabled, but following E-mails end up as deferred, but I disabled, enabled and requed mail ... failed
10. Checked fail2ban isn't listing 127.0.0.1 (I'm trying everything now!). Not listed...
11. The machine has disk, cpu usage is in the few percent range, memory usage has been flat (albeit did jump a couple of hours ago, but that was hours after these lost connection errors were first being reported)
12. The problem is affecting both the delivery of inbound message and sending of outbound, both with the same "(lost connection with 127.0.0.1[127.0.0.1] while receiving the initial server greeting" error

 

[iainh]

Ah ... I knoew it. As soon as I post, I'll find the fix...

I recall in the rapid migration, SpamAssin is no longer availe and I presume has been incorporated into Plesk Email security. I therefore looked at Warden Anti-spam and Virus Protection, but didn't go through with licensing it. All has been well for the last few weeks, but obviously overnight the 'inactive' componment 'did something', and what it did was the block mail delivey.

So Warden is now uninstalled and in the bin. Will take a look at Plesk Email Security, but see this now wants a licesne fee whereas good old SpamAssassin was free. Progress?