Change envelope sender for forwarded messages?

[PSI Mailbag]

> Thanks, Norbert. That certainly looks like one possible solution. I'll
> also look at Julian's .forward with sendmail -f suggestion, though I'm
> not sure I can use .forward files in conjunction with dovecot deliver
> LDA (which I want to use for sieve filtering).

I'm not sure if this will work with dovecot's LDA, but you could set up
an alias that pipes into a script (Perl or otherwise) to do the
rewriting for you. After you have that in place, you could use a
non-spam forward function to hit the alias (or whatever other method you
prefer).

I've only ever specifically tried it with procmail, but it might work in
your case too.

 Cheers,
-Joshua