Well, my hat is off to Cory Doctorow who pointed out on the "Fair and Balanced" boingboing yesterday that there is a way out from the hell that is Apple's Mac Mail client for OS X. Don't get me wrong, the client is very slick. But one of its little niceties (adding each recipients email address to a temporary "history" file) really slows outbound mail delivery...I've clocked over 20 seconds of the death Frisbee from time to time.
Cory's solution? Not to dump Mac Mail, but to just give its Address Book a little nudge, forcing it to rebuild its datastore. You can read his note, or you can just create eight or so new entries in your address book, deleting them thereafter. Presto, no more endless moments waiting for the "adding one of one addresses to address book"message. Funny how after weeks of moderate pawing through Apple's support site, this is the first mention I've seen of this problem and a solution.