Resolved IMAP not working with STARTTLS or SSL/TLS Mailserver Dovecot Problem

[lberens]

Server operating system version

Ubuntu 18.04 x86_64

Plesk version and microupdate number

Plesk Obsidian 18.0.51.1

I encountered a strange behaviour happening since yesterday.
System:
Product version: Plesk Obsidian 18.0.51.1
OS version: Ubuntu 18.04 x86_64
Build date: 2023/04/04 17:00
Revision: 5f28ac65ab7698d3411bcb7b25e11dabc0d59dd9
I also use Plesk Premium Mail.
The internal Database Server crashed just before me noticing this behaviour. "plesk fix" found some problems with the db but fixed it. So even though it could play a role i don't think so at the moment.

Behaviour:
I cannot connect to any of my Subscriptions via Mail client (IMAP). At least as long as i choose Encryption STARTTLS or SSL/TLS. If i try it without encryption it works.
My Thunderbird client throws out the following logs:

[Parent 280084: IMAP]: I/IMAP 23dea100:thedomain.de:NA:CreateNewLineFromSocket: clearing IMAP_CONNECTION_IS_OPEN - rv = 80470002
[Parent 280084: IMAP]: I/IMAP 23dea100:thedomain.de:NA:TellThreadToDie: close socket connection
[Parent 280084: IMAP]: I/IMAP 23dea100:thedomain.de:NA:CreateNewLineFromSocket: (null)
[Parent 280084: IMAP]: D/IMAP SetConnectionStatus(0x80470002)
[Parent 280084: IMAP]: I/IMAP 23dea100:thedomain.de:NArocessCurrentURL: Enable of STARTTLS failed. Error 0x80470002
[Parent 280084: IMAP]: D/IMAP SetConnectionStatus(0x80470002)
[Parent 280084: IMAP]: D/IMAP URL failed with code 0x80470002 (imap://info%40maildomain%[email protected]:143/discoverallboxes)
[Parent 280084: IMAP]: I/IMAP 23dea100:thedomain.de:NArocessCurrentURL: aborting queued urls

My maillog looks like that if i try to connect with encryption (the remote IP of the client is not even shown in the logs, just like dovecot is not even getting the request properly):

Apr 12 16:21:58 h2920728 dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 0 secs): user=<>, rip=127.0.0.1, lip=127.0.0.1, secured, $
Apr 12 16:21:58 h2920728 dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 0 secs): user=<>, rip=127.0.0.1, lip=127.0.0.1, secured, $

I tried re-issuing the ssl certificates, restarting the server, trying to change the certificate used for each subscription (for the mail) - nothing helped.
Also good to know: this system is still hosted on one of these awful strato V-Servers with a ridiculous low numproc value. i thought this could be the issue... but i do not appear to run into a bottleneck. especially since it works without encryption. i will move servers very soon to eliminate the possibility of issues because of strato in the future.

Also: it is not an Fail2Ban issue - my tests were completed with a fixed ip that is excluded from F2B.

Maybe someone can provide another perspective on the issue or even provide a solution! because i am honestly stuck right now. My last resort would be to move all Subscriptions over to another server.

Would appreciate any help on this!
Best regards

 

[mow]

Just curious: Do pop3 or SMTP work with SSL?

 

[lberens]

Hi, SMTP does work without a problem. I will need to test Pop3.
I read a lot about issues with Plesk Premium Mail and SSL - sadly i could not find a fix yet - but it sounds like, it could be a Plesk Premium Mail issue.
Anyone knows if it is safe to uninstall and reinstall Plesk Premium Mail? Will Calendars and Contacts still be saved? Or will i need to make separate Backups of Contacts and Calendars?
Best regards

 

[lberens]

Well - i fixed it. If anyone else experience something similar - delete the extension "Plesk Premium Mail" and reinstall it. dont forget to install the dependencies in the Plesk Premium Mail Tab again. I assume the problem was a corruption in the DB because of the DB Server crash. it was not possible to track down why this issue appeared. But well - at least it is fixed now.
PS: removing the Plesk Premium Mail Extension does not delete Calendars or Contacts. they are available again after the reinstall for premium mail users.