Just a note: adding <confirm> to the first of the subject does work as a confirmation, but I believe it only works to confirm messages sent TO other BlackBerrys.
Here is the text of the confirmation email sent back to me:
"Your message:
TO:
![[email address]](http://www.blackberryforums.com/?emailimage=19de3280818845098e0c6afe015f466f)
SENT: Mon May 21 12:31:23 2007
SUBJECT: <confirm>. Test again
has been delivered to the recipient's BlackBerry Handheld."