I must confess not to know which specific settings Pine allow, but from what is normally possible by MUA settings I have to say: the MUA
New option in 4.50+ above that lets you disable the Sender header altogether.
I also wrote a patch to remove it: http://www.enzotech.net/pine.html
it was a major complaint for people using roles, that you could always see the real account within the Sender header.. so, we removed it. :)
