Connection to postfix mail server from thunderbird.

Hello

i have set up an Webmin server and two domains attached. I can send mails from Usermin also recive.

Now i want to connect to the imap server from my phone and thunderbird. and here every things go wrong.

I think it might be an DNS CloudFlare problem? I have made a A record pointing to ip an MX mail pointing to ip also there is an MX domain pointing to domain. Can this be the issue?

Wich port should i use for in/out smtp - I have already assigned Lets encrypt to Postfix.

I really hope some one can help me with this stucked issue.

Best regards.