Mail Server on Docker: sanity checks
[UPDATED 21/3/2022]
I have a shiny mail server on gioorgi.com. I decided to manage it on first person because it is important to have tight control on your email, in my humble opinion. It is not strictly necessary, but lending your email address to big company like Googles, Microsoft, Yahoo and so on could be a issue if you get banned by them for whenever reason.
Let's take a look to some trouble I fixed in the past 2 years.
Firewall: First of all
For firewall settings refer to this documentation and close all other ports.Banned IPs
I had some troubles sending mail to Hotmail: they banned my IP. So I find out this fantastic site which will check for you a tons of things, like correct DKIM signature and so on.So I was able to open a ticket to Microsoft exposing the issue. And it is incredible, a real guy answered (or a super AI-azure powered robot running on WindowsServer...I dunno but I think it the guy is cheaper).
Microsoft solved the issue in a week, smooth like a glass.
Extra tip: refer to https://www.rackaid.com/blog/hotmail-blacklist-removal/ too for a list of tips