Mail Receiver App Discussion Summary
The discussion revolves around the Mail receiver app, specifically the use of two port numbers (25:25) for SMTP. Andro is trying to run a Postfix server for mail on the same server as a Discourse container, but the mail-receiver app is occupying port 25.
pfaffman explains that the two port numbers represent the external IP and the IP inside the container, a fundamental concept in Docker. Andro is looking for documentation on this topic and is trying to find a solution to route messages for a specific domain to a different port.
Andro is considering changing the mail-receiver SMTP port and using LMTP to route messages from Postfix. pfaffman suggests that this is a Docker fundamental and points to a previous discussion on the topic, Postfix and mail receiver.
Where is the best place to ask about mail receiver topics? Here, or another forum?
Specifically I am after details on what appear to be a pair of port numbers (25 : 25). It’s not clear to me why there are two ports here, not just one for SMTP. I cant find documentation in github.
Are you talking about Straightforward direct-delivery incoming mail?
The first 25 is the external ip, the second is the ip inside the container.
What problem are you trying to solve?
Thanks. Where is that documented?
Problem - trying to run normal enterprise class Postfix server for mail on same server as Discourse container. I need to have email for other websites, but mail-reciever sits on SMTP port 25.
For lack of other guidance I thought I could attempt to change the mail-receiver SMTP port and use LMTP or something from Postfix to route messages for that domain to that port. But I am rather lost.
It’s a docker fundamental. Most any “how to use docker” guide covers it, I’d think.
I gave an answer to this question over at Postfix and mail receiver - #5 by pfaffman.