I don't see a lot of merit in making them similar to the SMTP verbs.
Even really clueful users (ones capable and willing to write raw Sieve
scripts) don't know much about SMTP, and making them type "rcpt" doesn't
seem like the right thing to me.
Well, this (hopefully :-) clueful user finds mail-from and rcpt-to to
be much more intiutive than the alternatives.
--lyndon