Years ago I spawned an iredmail install that made a fully smtp/pop/imap/webmail/webdav/calendar setup that I've never been able to get quite fully working manually assembling each myself over the years. Mail is simply a pain, iredmail made it less so.
Years later, I pay for a gapps domain from google for myself, money well spent not do deal with ^^^.
I like having a shell around I can bop into and test things from on "the internet", so it's handy. I'm doing AWS training, probably going to fire up some instances there to play with next.
-mb