sync-server without deletes?

[Shuvam Misra]

> > > With the new replication engine in 2.4, it will be possible - deleted
> > > messages still get replicated for a week - and if you set an explicit
> > > long expiry time on the replica (say, years!) then it wouldn't get
> > > cleaned up any earlier.
> > 
> > That sounds like it's what we want, so I'll plan on moving to that. In
> > the short term perhaps I'll just need to copy to a common folder as you
> > indicated, or have postfix just send a duplicate copy to our long-term
> > backup server.
> 
> Well, unless you have users delivering mail to each other through IMAP
> on shared folders, one usually configures the MTAs to drop a copy of
> everything into a system mailbox...

Yes, this is what we do too. We have a milter in Sendmail which adds an
envelope recipient for each mail passing through Sendmail. This new
recipient is a system mailbox which holds the mail archive. Once a day, a
cronjob moves all mails out of Inbox to a freshly created mail folder
whose name contains today's date, thus preventing the Inbox accummulating
millions of messages over time.

It's quite simple, and it doesn't provide for an easy searching of
the archive the way a search engine would do, but it's very reliable.

One of the biggest differences between this approach and any IMAP
replication based approach is that you can send an outgoing mail in the
latter approach without it being recorded. (Take the worst-case situation
where a guy disables his copy-to-Sent-folder flag and sends the mail, or
even does a telnet to the SMTP port and hand-crafts the email.) In our
approach, each and every outgoing mail also gets captured in the archive.

Our solution can run any number of mail servers, hence the message can
actually go through multiple MTAs before leaving the organisation. We
make an archive copy at each MTA, thus wasting bandwidth to deliver
redundant copies to the archive. But on disk, only one copy is stored,
thanks to the de-duplication facility of Cyrus. :)

regards,
Shuvam