[MlMt] Disable saving sent mail altogether?

[Sam H.]

Hello all,

I know about the hidden prefs MmSentMailbox, etc., but what I really 
want is to disable saving sent mail altogether. If I make sure that no 
mailbox has Mailbox Type > Sent Messages, Mailmate creates a new “Sent 
Messages” folder.

I Bcc all mail to myself, so saving sent mail in addition to that is 
superfluous.

Is there a way to convince Mailmate not to save sent mail anywhere? 
Thanks.
-sam