Can't connect Thunderbird with my smtp server
Please inform me if I'm missing something cause I'm lost after one day of searching google and other sources.
I have a smtp server behind a NAT router that's working fine (with the help of my ISP's relayhost smtp server).
Dovecot is running on the same machine using the IMAP protocol.
I can send/receive mails from the server without issue and dovecot is running listening on all addresses.
When I'm trying to connect Thunderbird using the external domain name (example.com port 143) it "can't find the settings on my e-mail account".
The dovecot server is running with minimal settings (plain text password connections)
If I configure Thunderbird to use the server's internal address (private IP address) from inside the network everything is working without issue. (I can send receive mails).
Now, you might say I have something blocked from the outside.
That can't be true because I tried from another network and I could successfully connect to dovecot using telnet example.com 143 but again, can't do it using Thunderbird.
From the telnet session I could connect, authentificate and fetch mail items.
Ports 25, 143, 110 and 53 are all forwared to my internal server's IP address and are open from outside.
Is Thunderbird trying to connect using port numbers other than 143 and 25? Perhaps I need to forward a couple of more port numbers if so.
Thank you very much for your time in reading my post.