The opportunity is to have a highly unified, configurable email system.  But there are challenges with each of the system emails:

sign-up email

notify someone of a new Account Request

This is probably the one we could do fastest, but

• might have trouble making the from address use the creator's account.  It's critical that it be in there somewhere...

account info email

send someone their login details

This email is triggered by a weird pattern of events.

• Sometimes it's not even a card creation (forgot password), which could make this tricky to do with flexmail at all  (or we might have to expand flexmail's repertoire)
• It's usually sent immediately after a user card is created, though sometimes that's an invitation/approval, and sometimes its a signup.  Will that be weird?
• the content is not just simple content -- it involves generating a new password

HOWEVER - this is the one we've gotten the most requests to customize.

change notice

notify watcher of a change in a watched card

• integrated with interface
• tracks action (update, edit, etc)
• tracks subedits