[Dovecot] duplicates with multiple To/CC and sieve redirect copy

[Adam Szpakowski]

Hi,
In one installation we are using sieve "redirect :copy" to create copy 
of the incoming email (local boss gets copy of its employees mails).
There is a problem when the incoming email has multiple To/CC entries 
with local users. Multiple copy/redirects are created (one for each 
employee) and there are multiple copies in "boss" account.
Each of this emails has the same Message-ID.

Is there a way to detect those duplicates and discard them when saving 
copies into boss account?

There was a discussion on the list a while ago (Feb 10/11, 2011) 
mentioning this problem, but with no clear solution.

We are using Dovecot 2.0.15. Mail is delivered via LMTP (MDA/postfix is 
on separate machine then MAA/dovecot).

-- 
Adam Szpakowski