Cannot setup email client

I have a new virtualmin installation that has about 5 virtual servers in it.
The server runs on Ubuntu 16.04.

I am unable configure email clients like thunderbird to work. Everytime I try to setup an email account in thunderbird, I get a
“Thunderbird failed to find the settings for you email account.” I followed the docs tutorial on setting email up but I wasn’t able to get email setup to work.
I also added copied SSL certificate to dovecot and postfix.

I am not sure what I need to do here. The virtual servers I have were imported from a cpanel server.
Please tell me what to do or what I’m missing. Thank you.

I can receive and read email through usermin. Sent mail gets queued and doesn’t get to recipient.