To keep myself sane and practically eliminate the need for bayesian spam
filtering, I have my mail server set up to use adhoc aliases.

When an incoming message gets received, it looks to see whether there's a
hyphen in the local portion of the address (as in,
'foo-something@mydomain.net'). If there is, it delivers the message to the
account matched by the text on the left side of the hyphen, but preserves
everything on the right side for downstream spam filtering. I make up new
addresses for everyone who sends mail to me (like 'foo-dad@mydomain.net',
'foo-amazon@mydomain.net', 'foo-someonelikely2spam@mydomain.net', etc). That
way, if someone's address book gets sniffed by a trojan and my address falls
into spammer hands, all I have to do is set a procmail rule to silently
blackhole incoming mail sent to that alias, and make the person who used to
use that address send mail to a new address instead.

It works brilliantly. I no longer have to worry that some idiot friend or
coworker will carelessly destroy yet another email address of mine by sending
me a "free" online greeting card, or otherwise giving up my address in ways
that I myself never would. And when I encounter a website that extorts my
address, it's no big deal. I just make up a unique address for that site, and
if I start getting spammed, I just nuke that alias.

On a typical day, my procmail script kills about 24,000 incoming emails from
spammers sent to compromised aliases I've blackholed, and 99% of the rest are
good. When I find spam, all I have to do is check to see what alias it was
addressed to, add it to the blackhole list, and kick a note over to the
person to whom it originally belonged to let them know that future mail has
to be sent to a new address.

Therein lies the catch -- when replying to an incoming email message, I need
to have Outlook sniff the actual message to see what the address was (because
the actual mail server account literally tells only "half the story" -- the
part that would go on the left side of the hyphen), and allow me to easily
enter an arbitrary return address when I create a new message. For the past
couple of years I've used Thunderbird (which has always had a nice plugin to
do just that), but now that I have Outlook 2k7 handy to play with, I've
decided to give it a fair shot to see if it can do what I need.

Can it? How?