[BlackFly]

I can recommend reading about postfix architecture if you want to learn a bit about what would nowadays be called a microservice architecture:

https://www.postfix.org/OVERVIEW.html

You might need to know a bit about how email servers work to appreciate it though.

[pixelworm]

Well maybe I'll take some time to learn about email servers then. I use email everyday so I suppose it'll be good to know a little more about how it works.