Cyrus to replace UW?

Christopher Crowley ccrowley at
Tue Jul 29 10:01:58 EDT 2003

Brad -

We have a large ( 20K ) userbase, and I would like very much to change to
Cyrus.  However, it is not a drop in replacement for UW-IMAP from the user's
perspective.  They will need to change their root folder path, etc. We have
been thinking about this for 6 months.  It will probably take another year
to plan, document, and implement it.  If you don't have those same sorts of
user problems, you are using large mailboxes, and you want some more
management flexibilty, Cyrus is probably your best bet.

>From your perspective, in the migration you have a lot of mail to move from
one server to another.  There is a book on IMAP from O'Reilly which talks
about migration strategies.  You might consider something like perdition ( ) to help manage the migration, so
you can have both UW-IMAP and Cyrus running and a central perdition server
that manages the per-user connection.

( Sorry for the digression from Cyrus here. )
The other option is to look at the bandwidth to the current IMAP server,
check memory on the system, since UW-IMAP consumes a lot of memory for large
mailboxes.  You could use mbx indexed files instead of the plain flat files
with UW-IMAP.  From imap-200./docs/CONFIG:
" mbx format is encouraged if at all possible; "

mbx format is an indexed format that you can't edit directly, but has
performance advantages over the unix format mailbox. There is a lot of
documentation online for how to use mbx, and it is outside of the scope of
this mailing list to address it.  But it may not be your silver bullet.  You
should probably look at network throughput first, disk I/O, and memory
before you start making big changes to your current system.

Good Luck.

Christopher Crowley
Technology Services
Tulane University
ccrowley at
PGP Key ID: 0x7CF18FDB

----- Original Message ----- 
From: "Brad" <cyrususer at>
To: "Jason Fesler" <jfesler at>; "Cyrus Info Mailing List"
<info-cyrus at>
Sent: Monday, July 28, 2003 12:24 AM
Subject: Re: Cyrus to replace UW?

> Thanks for your reply Jason.
> I will look into it, although from your description it may be a bit beyond
> I wonder if Linux will ever be ready for the masses? It is still way too
> technical for the average user.
> However, I'll have a go.  ;-)
> Cheers,
> Brad
> On Monday 28 July 2003 14:53, you wrote:
> > > I have a Red Hat 9 mail server running UW imap and I find that mail
> > > retrieval from both Windows and Linux email clients is very slow, even
> > > the extent that the email client sometimes times out waiting for the
> > > server to respond.
> >
> > I regularly open 20,000+ message mailboxes with pine against cyrus.
> > generally takes <2 seconds to open for me.   "Normal" size mailboxes
> > take any perceivable time at all to open.  Your mileage may vary with
> > windows clients, as they typically want to download all the headers -
> > however, they won't be stalled on the server end scanning
> > /var/mail/lusername.
> >
> > > I have heard that the Cyrus imap server is somewhat faster and was
> > > wondering if replacing the UW imap server with the Cyrus server would
> > > solve my problem.
> >
> > It might.  The road there is long though.  If you are a do-it-yourselfer
> > who doesnt' mind getting dirty, reading *docs*, etc, you'll find that
> > cyrus is way way worth setting up from a performance and security point
> > view.  I won't say setting up cyrus was easy for me though.
> > use of docs, use of the web search features of your favorite search
> > engine, etc all pay off big dividends.

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