@body['sender'] = sender
I doubt that is going to work like you want it to. "Sender:" is a
fairly magical header that's used by MTAs to let MUAs know which
envelope sender was used, so depending on the exact details of your
mail setup that line may work as you intend, be deceptive or be
For my own application, I wrote a tiny plugin that monkeypatches
ActionMailer to allow setting the sender as it should be (in the SMTP
dialog for :smtp, with -f for :sendmail). I don't have a public svn
server to easily publish it from, but I could post it here, I guess.
If there's interest.