[Dovecot] Discard duplicate messages at delivery?

[Nicolas KOWALSKI]

Hello,

I am using dovecot 1.2.9, and the sieve plugin for filtering incoming
messages into specific folders. The MTA is postfix, and deliver is
called using the "mailbox_command = /usr/lib/dovecot/deliver"
directive. 

Is it possible to make dovecot's deliver discard duplicate messages?

With cyrus there is a duplicatesuppression directive which works well
(http://cyrusimap.web.cmu.edu/imapd/overview.html#duplicate). With
procmail, this can be done with the following recipe, but I did not
found an equivalent for dovecot:

# One often receives duplicate messages for cross-postings to mailing
# lists, or explicit replies to a post from you in addition to the
# mailing list message.
# 
# The following recipe eliminates all duplicate messages. It tells
# formail(1) to keep a cache file of the Message-IDs of the most
# recent messages you've received. Since Message-IDs are guaranteed
# unique for distinct messages, they are ideally suited to weed out
# duplicates.
# 
:0 Wh: msgid.lock
| formail -D 65536 .saves.msgid


Thanks,
-- 
Nicolas