https://github.com/foxcpp/maddy
https://blitiri.com.ar/p/chasquid/
These options are much easier to set up, will do things like generate DKIM for you, etc.
I talk about this a lot[0]. There are positively awesome tools for email out there.
[EDIT] - Since I'm repeating myself I've collected all the options into a post[1] I can just link to.
[0]: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
[1]: https://vadosware.io/post/its-never-been-easier-or-harder-to...