I #Selfhost my email server (that handles my 20+ domains) since almost 20 years now, currently on a cheap virtual machine running Linux, with 1 CPU core, 2G of RAM, 40G hard drive and unlimited network traffic which costs me less than β¬5/month.
Many people keep on telling me that running your own email server is more or less impossible. I simply don't listen to them.
I explained my setup in a blog series starting at https://jan.wildeboer.net/2022/08/Email-0-The-Journey-2022/
Jan Wildeboer

@jwildeboer @homelab
Hear hear! i have also been running my own email for about that long. 23 years according to the age of my domain name registration. Started out on a shared hosting server, moved up to a VPS, and for the past decade have been on a dedicated server. (i also use it for a couple of websites, some offsite backup storage, and misc dev work.)
There is a learning period, and i will admit that as someone who has a couple of decades of experience in the webhosting industry am not just an average person, but really the hardest part is the initial setup. After getting the basic server, i set it up to automatically install updates every night and did some basic security hardening, like disabling direct login as root via ssh, but other than that it's pretty hands off. As a small site it's not a target for any specially directed attacks and i've never had a security breach that i know of.