My journey in setting up email

I've recently created a new email address, [email protected]. If you want to set up email yourself, just get a VPS with port 25 unblocked, and run docker-mailserver. The config that I use can be found here. This post is going to detail my far too difficult journey in setting up email.

Firstly, I can't host email at my house. Email, specifically the Simple Mail Transfer Protocol (SMTP) runs on port 25, which is blocked by most consumer ISPs including AT&T to prevent users from accidentally creating open relays. This meant that I had to get a VPS. I decided to go with Linode because I'd heard good things about them. As it turns out, Linode also blocks port 25 so the first several hours after buying the VPS was spent trying to figure out why nothing was working at all before realizing I had to file a support ticket to get port 25 unblocked.

After that, I decided to try and find a dockerized mail server. I'd already known about Luke Smith's emailwiz script, but I really wanted a dockerized solution for extra portability. Going through the options, there's axigen (propriety trash), mailcow (too much memory usage), iRedMail (docker image is unstable), Apache James (bad documentation), mailu (didn't work for reasons I will explain later), and docker mailserver (also didn't work for the same reason as mailu).

After spending a couple of days going through all of these options, I decided to give in and use the emailwiz script. After sending the first few emails my Dad wanted to set up his own emails on his own domains. The configuration that emailwiz creates email addresses based on the users on the system. My VPS had a user called nate, and the domain name in my VPS was natechoe.dev, so the email [email protected] was created with the same password as my user password. This configuration, you may notice, does not allow for email addresses to exist on some domains but not others, or even for multiple domains to be served by one email server. Going back to the drawing board, I realized that docker-mailserver did have support for multiple domains, but first I'd have to set it up correctly. After several hours of trying and failing to set up a mail server, I noticed that some of the log messages I was seeing looked exactly like the log messages that I wrote for my web server. Messages such as

[2022-06-13T03:17:25Z] Accepted stream
[2022-06-13T03:17:25Z] poll() finished with 1 connections
[2022-06-13T03:17:25Z] Obtained file descriptor from child
[2022-06-13T03:17:25Z] poll() finished with 2 connections

To bring this entire journey to a quite anticlimactic conclusion, as it turns out docker-compose container names are based on the last subdirectory path that the docker-compose file is in. Because my mail server was in /root/mail/natechoe.dev and my web server was in /root/natechoe.dev, docker-compose thought that the mail server and the web server were the same natechoe.dev, and binded to the wrong container.

So what's the moral of the story here? docker-compose names containers based on the last subdirectory name? Read the error messages you get from the programs you use? The solution may be right under your nose? Really I have no idea, this is just a frustrating story about setting up an email server.