TSL/SSL failure: Unexpected TCP input disconnect

christof

I'm receiving the following error message:
TLS/SSL failure for mail.example.com: Unexpected TCP input disconnect

I'm using these IMAP settings
Host: mail.example.com
Port: 143
Protocol: IMAP (→ we do not have SSL)

Regarding the environment
Server: Microsoft-IIS/10.0
osTicket: v1.12-20-gd2a7182d (d2a7182)
PHP: 7.2.14

osTicket worked until TLS was changed from TLS 1.0 to TLS 1.2 on the mailserver. Unfortunately, I cannot revert TLS settings.

PeopleInside

christof Hi, TLS 1.0 has security issue so it's good you have moved to TLS 1.2.
Do you have issue only with OsTicket? I mean, have you tried to configure the email address in a email client and do you see any warn about the certificate?

Do you have the same issue if you configure POP instead of IMAP?

christof

PeopleInside Thank you for your reply.
We have the email address configured in MS Outlook and it works without any problems. No warnings about certificate whatsoever.
I cannot configure it from IMAP to POP: We don't use POP and we wouldn't be able to move incoming mails to a specified folder.

PeopleInside

christof You don't have to configure the email address in the client as POP but in OsTicket.
I see that IMAP on my business domain did not work, if I use POP work.

Is just a try.
If the issue persist try to see error server log or if the email address is managed by the server check email logs.

Have you tried to choose IMAP+SSL? Maybe works also for TLS?
IMAP port usually is 993 and 465 for outgoing email.

christof

PeopleInside Thank you again for you reply.
I tried it with POP inside osTicket, receiving: Can't connect to mail.example.com,110: Timed out
When I try IMAP+SSL, the following error appears: Can't connect to mail.example.com,993: Timed out

Other things I've tried:

Updating SMTP.php and Socket.php as described here:
https://github.com/osTicket/osTicket/issues/3726#issuecomment-344398410
Upgrading from PHP 7.2.14 to PHP 7.3.12 respectively PHP 7.4 as described here:
https://forum.osticket.com/d/94450-resolved-unexpected-tcp-input-disconnect

Is there any way to pin down the root of the error "Unexpected TCP input disconnect" (more detailed error log)?

PeopleInside

christof I don't know if the issue is the email address you are using.
GitHub topic mentioned is very old, i dont know if is a good idea edit recent OsTicket files.

christof

PeopleInside

i dont know if is a good idea edit recent OsTicket files.

Don't worry, we've got everything backed up :-)