I have this (personal) account, and an office account. I've already set up
a recipe to forward personal mail from this acct to my work account. Now I
want to set up something so I can send mail from work with the header
x-pbjfwd: <recipient address>, procmail will intercept it and mail it to
the address in the x- header, so the recipient sees it as from the personal
account (instead of mailing to address A and receiving a reply from address
B). 
Here's what I've come up with, but I'm not sure I have the whole formail
thing figured out:
#Forward mail FROM pjanus(_at_)audit(_dot_)navy(_dot_)mil with x-pbjfwd
# header out to the recipient
:0
*^x-pbjfwd:*
{
  :0c   
  formail -x x-pbjfwd: > fwdaddy        
  formail -I "To: $fwdaddy"
  |/usr/lib/sendmail -t 
}
TIA!
Philo
Finger for public key                   philo(_at_)radix(_dot_)net
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Paranoids are people, too; they have their own problems.
It's easy to criticize, but if everybody hated you, you'd be paranoid 
too.