[Dovecot] On-delivery deduplication?

[Heiko Schlittermann]

Xin LI <delphij at delphij.net> (Wed Jun  8 22:04:51 2011):
(…)
> A feature of Cyrus-IMAPd I really missed after migrated to Dovecot is
> their optional "duplicate suppression", which eliminates duplicate
> message at deliver time, if their envelope sender, recipient and
> message-id matches.  

Not sure, but I *think*, cyrus does dedup based on the message id and
recipient only.

> For example, if one subscribes to a mailing list,
> and someone hit "Reply All" to reply to him, there will be two different
> SMTP deliveries, one from the replier's server and one from the mailing
> list.

If your above statement about the dup detection is true, these two
messages will be delivered both, since the envelope sender is likely to
differ (most if not all list servers replace the envelope sender for
several reasons (bounce detection, SPF passing, …))


> Is it possible to do the same on latest Dovecot?  (Looking at the
> documentation it seems not?)  Or is there some better ways to implement
> the same functionality?

And these two messages are no duplicates. They differ in the headers, 
probably they differ in parts of the body (signature of the list 
server), EVEN they carry the same message id!

A duplicate is a duplicate if the message and its copies are identical.
And from MPOV this is very unlikly to happen in common environments.

OTOH, if you need such feature, it shouln't be too challenging to write
a MDA replacement, that decides about duplicity and finally passes the
remaining messages to the Dovecot MDA.

-- 
Heiko :: dresden : linux : SCHLITTERMANN.de
GPG Key 48D0359B : 3061 CFBF 2D88 F034 E8D2 7E92 EE4E AC98 48D0 359B
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 198 bytes
Desc: Digital signature
URL: <http://dovecot.org/pipermail/dovecot/attachments/20110608/fbb20491/attachment.bin>