Love it.  `Mail` definitely looks like the way to go.

In the future, we might want to let applications style their messages.  Just linking to CSS doesn't work, you have to actually type out the styles inside each element that you want.  There are gems for this, see https://github.com/fphilipe/premailer-rails and http://stackoverflow.com/a/6230228/1664216.  Do we need to do anything to the API now to support adding this to v1.x in the future?