[Dovecot] IMAP/POP3 server with proxy feature

[Chris Wakelin]

Jasper Bryant-Greene wrote:
> We are currently evaluating the migration from a proprietary, legacy
> mail server onto Dovecot for 20,000+ virtual domains. This is a big job
> and we intend to do it by initially proxying connections through to the
> legacy server, and moving customers over in batches by turning off the
> proxy feature for them.
> 
> In the manual it states "This model is still a bit unfinished in current
> code" [1]. What is needed to get this production-quality? I'm happy to
> help out with any work required.
> 
> [1] http://wiki.dovecot.org/ImapProxy

I don't think you need that particular feature. As far as I know just
use a passdb with extra-fields and have "proxy=y" defined for the users
you want to proxy. I think this is pretty stable.

We're planning to use a passwd-file for an extra passdb containing
things like:
<username>::<uid>:<gid>::::destuser=<username> host=<proxied server ip>
port=143 nodelay=n nologin=y proxy=y

Then:

...

  passdb passwd-file {
   args = /etc/dovecot/proxied-users
  }
  passdb pam {
  }

...

Dovecot uses the proxying feature itself for SSL connections, so it
should be pretty robust.

Best Wishes,
Chris

-- 
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Christopher Wakelin,                           c.d.wakelin at reading.ac.uk
IT Services Centre, The University of Reading,  Tel: +44 (0)118 378 8439
Whiteknights, Reading, RG6 2AF, UK              Fax: +44 (0)118 975 3094