Awhile back I started requiring TLS for connections to my mail server. Not only is this not standards compliant from what I recall, but I've noticed a disturbing amount of other mail servers that apparently require plaintext connections. Most notable is password and college application information which couldn't be delivered to me because their mail servers refused to use TLS. The college in question was kind enough to look at their logs for me and see the issue, and ask me to disable TLS to receive the information. Of course this doesn't solve all the problems. Mail is still stored in plaintext, at least until I figure out a workable solution for that, and there's probably still the possibility of MITM attacks, but I feel at least requiring TLS is a step in the right direction. Until email is finally abolished, anyway.