Dovecot Error: Password Mismatch

[themetman]

I have Postfix vertsion 3.3.0, Dovecot Version 1:2.2.33.2 and PostfixAdmin version 3.3.10 using MySQL on a small device running Ubuntu VERSION="18.04.6 LTS (Bionic Beaver)" for my internal LAN Mail.
I have a user [email protected] with a mailbox setup in PostfixAdmin with a password as 'Test75?'
Everything is running fine, but I cannot get my Email Client Thunderbird to connect.
I have setup the debugging to see that the correct password is being used, which it is, but I have this error:

dovecot: auth-worker(26468): sql([email protected],10.6.10.10,<gB77wjLXGLsKBgoK>): Password mismatch (given password: Test75?)

showing that dovecot disagrees!!!
Why is this? Is it something to do with the permissions in PostfixAdmin?
I did find a post on Server Fault where someone had the saem problem. He just tried various passwords until he found one that worked!!!! I have not found any other post about this exact problem.
I am not adding the link to the Server Fault Post, because the last time I tried to put this post up with the link, I was blocked from this site.
Any help much appreciated.

 

[factor]

Postfix vertsion 3.3.0

You are in the wrong forum. Directadmin uses Exim not Postfix. This isn't the The PostfixAdmin forum.

 

[themetman]

OK, many thanks I will look further afield.