Subject: best choice

From: [email-masked] (Mark J. Bailey [HOME])
Date: Thu, 22 Feb 1996 09:02:15 -0600 (CST)

hi IMAP list readers,

i have a client that is on MicroSoft Mail right now (about 650 users).  Anyway
they are interested in having me research possibilities of IMAP has a 
replacement for the postoffice structure they currently run (on Novell).

What commerical and practical options are available to me using IMAP?  Ie,
which of the commercial IMAP capable clients for windows would a) work the
best (fastest) and b) be most easily migrated to from MM?  Also, I have
read in the imap.software file that there is an IMAP MAPI service provider
module being worked on.  also that netscape 3.0 will have IMAP support.

but I have also heard that IMAP is slow with large mailboxes.  

whom of you on the list here have been this route and can you please share
some of your thoughts!  I would be most receptive!

Thanks very much!

Mark

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From: Mark Crispin <[email-masked]>
Date: Thu, 22 Feb 1996 09:53:11 -0800 (PST)

Mark -

In general, I hesitate to make any recommendations of one commerical IMAP
client over another (we're trying to promote IMAP from *all* vendors!).  Among
commerical PC GUI clients, I have some experience with AirMail (from AIR Co.
in Japan, not the program from Spry) and *very* limited experience with ECS
Mail (predecessor to Simeon)

In the freeware world, we have a natural bias for Pine.  ;-)

To address your comment about "but I have also heard that IMAP is slow with
large mailboxes", this is an extreme oversimplification of a much more complex
issue of performance.  Slowness with large mailboxes may be experienced with
*certain* implementations of IMAP using *certain* mail folder formats on
*certain* hardware configurations.  If you change any of these variables you
make dramatic changes to the performance results.

The most common instance of "slowness with large mailboxes" occurs when an
IMAP server is configured with the c-client based server using the standard
UNIX mbox format on a machine with inadequate memory.  Unless you require
compatibility with existing Unix mail tools and/or have ample memory on the
server, it is better to use one of the alternative mailbox formats supported
by the c-client based server.

Many sites make the mistake of buying an overpowered CPU but scrimping on
memory.  An IMAP server rarely consumes more than a handful of CPU seconds
during its entire lifetime.  Use the savings from buying a slower CPU to give
the server gobs of memory.  A good rule of thumb if you use UNIX mbox format
is to allow at least 1MB/connected-user.  You can get away with quite a bit
less if you use an alternative format.

The Cyrus server has its own unique mailbox format, thus getting the same
effect (put another way, Cyrus doesn't let you configure things badly, at the
cost of throwing compatibility out the window).  With Cyrus, the gotcha is
that you need lots of inodes, just as you would on a news server.  It is
possible that in the future c-client may support Cyrus' mail format or at
least a Cyrus-style format.

Some of our users routinely use IMAP with mailboxes of 5000+ messages using
tenex format; is this large enough for you?