It's probably worth at some point adding at least one example of actually then sending them mail somewhere via a local sendmail binary, and one for via SMTP. I

It's probably worth at some point adding at least one example of actually then sending them mail somewhere via a local sendmail binary, and one for via SMTP. IME if you provide an email sending library without email generation suggestions, or vice versa, yours users will do something completely unexpected (and probably not to your taste) for the other half. (note that I'm explicitly not complaining that you didn't already do that, given how recently you got started - just trying to make sure it's on your list of stuff to do because bitter experience says it's more important than you might initially expect :)