from header class btwn mutt and mailman?

[matt.price@utoronto.ca]

hey folks,

I've just realized that mutt has been sending out messages using a
private address (matt - at - derailleur - org) instead of the 'form'
header set in  my .muttrc:

set from = matt.price@utoronto.ca 

I tried 

grep -ir derailleur /etc/*

ad the only relevant entry I could find was:

mailman/mm_cfg.py:DEFAULT_EMAIL_HOST = 'www.derailleur.org'

so my question:  can mailman override mutt's 'from' header somehow?
It seems bizarre and unlikely.  But there's nothing at all in my
.muttrc containing the string "derailleur" -- so I don't see how mutt
would even encounter that address!

Anyway, I find it puzzling.  

thx,

matt