I don't know if anyone is having this issue or I am doing something wrong. I have a fresh install of aapnel running on a centos 7 container. I was able to install the mail server fine and everything looks correct but every time I try to create a mail account and then try to use thunderbird or outlook, I am getting unable to login error. I am using the same SSL keys as the hostname for my mail SSL and I can not find a solution on why I am unable to login. If anyone knows how I could fix this I would be very grateful. Please see the screenshot below. Thanks in advance. 
uable to login to mail server.
Did you try using roundcube?
phxwolf
have you try to reset the account password?