sieve (imap-flags) add any information in header

[Achim Altmann]

hello,

if is possible to use add imap-flags with self defined messages to add 
in the mail-header?

I would use this for an c++-prog was read this header after 
sieve-modification to do any actions.

sample:
sieve check any mail and are the rules true then add a number like 
1234567 in the header from the mail.
the original-mail is moved in any defined folder and a copy from this 
mail was had sieve modified send to an other local-smtp-gateway.

Iis this possible?

Thanks a lot for any helps

best wishes

Achim