Re: IMAP design implementation (Cyrus, Courier or WU) -FB wanted
On Sat, Jan 19, 2002 at 04:36:00PM -0500, Ted Knab wrote:
> windows/mac clients.
>
> I have decided to replace our current server with an Exim/IMAP combo
>
> either running Courier, Cryrus or WU-IMAP.
>
> I am hoping you will help me decide on the IMAP a good one.
>
Well, according to me, the main point is about local file storage.
I think UW-IMAP uses primarily "plain old" UNIX mbox format, which is
:
- very well known, compatible with just about anything
- easily corruptible (not NFS safe)
- needs some tweaking for IMAP support
- one file per mailbox, which is not very efficient for deletions /
updates of individual messages
Cyrus uses a proprietary storage layout, which includes local
databases :
- it's "meant for IMAP", one file per message
- it features a complete ACL system and quota support
- it's corruptible, and sometimes it's hard to figure out what's
wrong, and how to rebuild the right database
- I don't think it's NFS safe
- it's not simple : you can't just "play with the files", you have to
keep the databases in sync
Courier uses Maildir (the native storage format of qmail) :
- it's open, simple and efficient : one file per message, nothing else
- it's fully NFS safe, using a purely fs based locking mechanism
- it requires some tweaking for IMAP support
I've setup various mail servers, using mbox, cyrus and Maildir. And
I'm now "sold" to the Maildir format. It's "unbreakable", even when
different POP/IMAP servers and various MTAs play with one spool at the
same time. It's now supported by most MTAs (I use Postfix), and
various POP/IMAP servers (I've just tried courier, and I'm fairly
happy with it).
mbox will be painful (corruption will happen).
cyrus looks interesting, but once you're there, you can't use anything
else, because the storage format is quite proprietary (although it's
not secret).
So my best advice would be : go for a Maildir based setup. Use your
favorite MTA, and try Courier IMAP. You'll still be able to switch
MTAs, POP or IMAP daemons later.
--
Nicolas BOUGUES
Axialys Interactive
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