Re: MUA support for multiple from addresses

["John Levine" <johnl@xxxxxxxxx>]

>The chain of logic was like this: 1. We want to sign using DKIM. 

So far so good.

>2. For that we need to make sure each outgoing From address is something the
>domain owner is happy to sign for.

That's the problem.  What's special about the From: line?  Do you
check to ensure that signed mail doesn't contain viruses, or Ponzi
schemes or hate speech or child pornography or any of a zillion other
things that well run mail systems wouldn't want to send?

I let my users change the From: line to whatever they want, and sign
it all with my main domain.  If the From: line happens to contain an
address in a domain for which I have a signing key, I also sign with
that.

R's,
John