Date: Fri, 7 Jul 2006 13:18:46 +0100 From: Brian Candler <B.Candler@pobox.com> To: User Freebsd <freebsd@hub.org> Cc: FreeBSD ISP <freebsd-isp@freebsd.org>, Francisco Reyes <lists@stringsutils.com> Subject: Re: IAMP servers in FreeBSD for ISP Message-ID: <20060707121846.GA36201@uk.tiscali.com> In-Reply-To: <20060706235712.A1171@ganymede.hub.org> References: <cone.1152240742.658037.2598.1000@zoraida.natserv.net> <20060706235712.A1171@ganymede.hub.org>
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On Fri, Jul 07, 2006 at 12:00:17AM -0300, User Freebsd wrote: > >Anyone care to share what IMAP servers they have found to scale best? > > By far, IMHO, the best is cyrus-imapd ... it was originally developed by > Carnegie-Mellon University to handle their on campus email, and grew > quickly out of that ... > > If I recall your environment at all, one nice feature of it is that it > supports something called MURDER, which, effectively, is a way of having > your mailboxes literally spread out over multiple backend servers ... > all the mail comes in through ServerA, but, as an example, mailboxes a-m > get stored on ServerB, and n-z go to ServerC ... > > They've also just recently added a replication ability, so that you can > have backup servers ... ServerD is a backup of ServerB, ServerE is a > backup of ServerC ... > > The thing is, it would most likely eliminate, or greatly reduce, your NFS > requirements ... Conversely, it also means that it is not safe to use with NFS backends. So if you already have a good and/or expensive NFS appliance, you won't want to use Cyrus. Remember that Courier has a proxy front-end built in, so you can use a proxy cluster instead of an NFS cluster (or even have some accounts on Courier and proxy others to Cyrus; a very nice migration tool) If you do want to go the Cyrus route, there are some good papers from Cambridge University in the UK describing their setup: http://www-uxsup.csx.cam.ac.uk/~fanf2/hermes/doc/talks/2004-02-ukuug/ http://www-uxsup.csx.cam.ac.uk/~fanf2/hermes/doc/talks/2005-02-eximconf/ Actually I have very good experience of courier-imap + exim in a large ISP environment, but the vast majority of users were POP3, not IMAP. Also, although Courier's sqwebmail has a not particularly pretty interface, it *does* perform very well under heavy usage (I suspect much better than a PHP->IMAP solution) since it accesses the Maildirs directly. Regards, Brian.
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