Greetings -
On 10 Jan 2008, at 21:49, Chris Wakelin wrote:
With Dovecot's caching and indexing, things are much better, but
there is still a significant overhead on opening lots of
connections, I fear, especially for mboxes (moving to maildir would
help of course). I would consider using imapproxy (designed to
assist with this problem by caching the IMAP connections) but I'm
not sure whether it would help significantly.
Whatever you do, DON'T move to Maildir if you are using the Prayer
webmail software!
We have used Prayer here for many years with the UW IMAP server
backend and first Berkeley, then later MBX, format mail folders.
When we migrated new users to Dovecoe with Maildir folders we
discovered that Prayer does NOT like Maildir folders. The reason is
that Maildir folders are "dual-purpose": each can contain any mix of
messages and sub-folders. However Prayer is intrinsically designed to
ONLY work with folders that can contain messages or subfolders, but
NOT both. The result is that Prayer can show you the list of folders
to navigate around, but will not list any messages within any folder.
I checked with Cambridge and this is a known and documented
restriction with Prayer. Their solution has been to hack Cyrus to
prevent dual-use folders. (Timo kindly supplied us with a patch for
Dovecot 1.0.x to do likewise.)
We are thinking about moving to a different webmail platform soon, so
I am following this discussion with interest.
I can confirm that webmail software that uses persistent IMAP
connections is a big win: it not only lightens load on the webmail
server machine but also, more importantly, on the IMAP servers.
Cheers, Mike B-)
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