You would need to have a really big email list to justify maintaining your own server with either open source software or Sendy, which I realize isn't a big dea

You would need to have a really big email list to justify maintaining your own server with either open source software or Sendy, which I realize isn't a big deal for developers but you gotta figure your time isn't free, right? If your list is small-ish, I would suggest to go with a hosted solution like http://BigMailer.io http://BigMailer.io or other similar providers depending on your feature needs.