Tomas Fasth:
There is another twist on this. I venture to say that a Sieve implementation
MAY choose to forward a message using MIME encapsulation. In such a case
resent headers MUST NOT be inserted. This should be enough for seriously
considering Alan's suggestion.
I venture to say that it must not. Have you missed the following
paragraph from the -04 Sieve spec?:
The forward command performs an MTA-style forward--that is, what you
get from a .forward file using sendmail under UNIX. The address on
the SMTP envelope is replaced with the one on the forward command and
the message is sent back out. (This is not an MUA-style forward,
which creates a new message with a different sender and message ID,
wrapping the old message in a new one.)
Barry Leiba, Multimedia Messaging (leiba(_at_)watson(_dot_)ibm(_dot_)com)
http://www.research.ibm.com/people/l/leiba