[Dovecot] Vacation -- reply to another address than envelope from

[Vegard Svanberg]

Vacation (Sieve) replies to the envelope address. However, I have a
customer which receive e-mails from a service which sends e-mails on
behalf of a user (submitted through a web form).

So an e-mail would be like (envelope from and from-header is
webformfromwhatever at foobar.com):

From: webformfromwhatever at foobar.com
To: mycustomer at hisdomain.com
Reply-To: usersrealmailaddress at example.com

I need the reply to go to the reply-to address.

Can I handle this with Sieve?

-- 
Vegard Svanberg <vegard at svanberg.no> [*Takapa at IRC (EFnet)]