I really enjoyed the whole process of running my own mail setups, configuring Postfix or OpenSMTPd to do clever aliases and transports, setting up CARP failover

I really enjoyed the whole process of running my own mail setups, configuring Postfix or OpenSMTPd to do clever aliases and transports, setting up CARP failover relays, managing DNS records, experimenting with different SPAM-filtering techniques, SSL, IMAP, mailing lists, the works. It taught me a lot about networking and security and everything a good sysadmin should know. I find it sad that that‘s pretty much a waste of time now for most use cases.