"Stuart D. Gathman" suggested:
On Wed, 17 Aug 2005, Seth Goodman wrote:
Any domain that opts in to this gives up the ability to participate in
mailing lists. That is a heavy price to pay. If you make it From: _or_
Sender:, when it exists, you still get what you want while allowing those
domains to post to mailing lists.
My idea is to skip the blocking altogether. Just make sure that
the MAIL FROM domain shows up in either From or Sender, by
adding or renaming and replacing Sender if required. Presto,
the MAIL FROM domain is displayed in the worlds most popular
MUAs.
With all of these "modify a header to display what you want" approaches - where
they are done to the message before it enters (an unaware) MUA - you will have
to screen and filter _all_ original content to make sure the bad guys have not
already pre-modified.
Also, you will have to strip out the modifications you made when replying /
forwarding etc..
Chris Haynes