Thunderbird 3.1.10 Connection Refused

[Unga]

Hi all

I need to access an IMAP server at mail.server.com:45000. And the server uses a self-signed certificate.

Since it is not possible to add an exemption, I have imported the mail server pem file.

But the Thunderbird still complain "Could not connect to mail server Acct-Name; the connection was refused".

It doesn't come to the stage to ask the password.

Server logs doesn't show any drop packets from the firewall.

How could I solve this problem?

Many thanks in advance.

Unga