Setting Return-Path to From address

[Mark Nyqvist Hjarding]

Hello,

Here is a glance of my posting styles:
  (".*"
    (name "Mark Nyqvist Hjarding")
  )
  ("^[a-z]+\\+hjarding\\.dk"
    (address "spam@hjarding.dk")
    ("X-Homepage" "http://www.hjarding.dk";)
    (eval (setq message-sendmail-extra-arguments '("-a" "hjarding")))
    (message-mail-p)
  )

Sometimes I would like to change the from address when sending an email
and this works by just changing it in the Message buffer before sending
it. The problem is that the Return-Path is still set to the value of
address. Is there a way to force Return-Path to be the same as From? 

/Mark