I have run email servers for myself and businesses. Every single headache I have had was related to some user having a shit password or malware on there PC and then spammers send spam from their address.

My personal email server has been hassle free. I use https://mailinabox.email/ which you just run the setup script and tell it your domain name and everything is set up correctly. It sends me an email every now and then saying it needs updating and thats all.