Can I use it without port 25?

[saschabrockel]

Currently, I run a ntfy instance which already uses an MX record and of course port 25. The port is exposed to the internet and this works.

So this is ntfy.test.com. Now I created a new entry called *.trash.test.com. Of course the A record for trash.test.com as well.

I run the OpenTrashMail instance in Docker and have mapped the internal port 25 to 2626 and exposed 2626 as well on my router. But I do not receive any mail. Where is the problem? Does it has to be used with port 25 and I can only use one tool?

I don't understand how this technically works anyway.