This would streamline sending e-receipts, newsletters, etc. which is currently a glitch-prone feature in RE that keeps no confirmation that the emails went out (only an exceptions report).  I really like the MailChimp emailer, but Raiser's Edge doesn't talk to MailChimp very well.  Maybe just integrate into MailChimp since they've already got a great system and then eventually phase in another option that's free.