Dovecot and Cpanel issue!
We setup a Cpanel server recently then we started to put customers on it. Right away we had a customer tell us they were not able to get email. They were getting the following error when checking email from a help desk.
SECURITY PROBLEM: insecure server advertised AUTH=PLAIN
Retrying PLAIN authentication after Authentication failed.
First thing that came to thought was that it is using Plain Text Authentication but it is not working for whatever reason. We tried to setup email accounts in outlook and they could send but not receive. POP3 was not working. I googled around and found someone with the same issue. We played with the server a little but then switched to the old default email server in Cpanel, Courier. Once we did that all outlook accounts and the support desk started working immediately. I do not know if this is always broke but it sure wasted about 2 hours of my time. I think I will stick with Courier in the future.