Re: Zimbra + IMAP

[Steve Hillman <hillman@sfu.ca>]

----- "Robert M. Thompson" <ab5602@wayne.edu> wrote:

> Hi Steve,
> 
> We are also currently in the process of investigating Zimbra to
> replace our current Mirapoint install.  I don't think IMAP would kill
> your Zimbra setup, but I don't have any direct experience with
> high-volume Zimbra+IMAP either.  IMAP is a relatively light protocol
> and fairly efficient at allowing remote access to email.  Currently,
> we support IMAP for around 35,000 users with Mirapoint and see fairly
> heavy use with minimal impact to our servers.

If your primary usage is IMAP, you'll definitely want to grill Zimbra folks on how they think it'll hold up under that kind of load. The Mirapoint servers were built for large IMAP, so they can deal with it. Zimbra is Java based, with all connections being handled by one Java VM per mailbox server. IMAP wants to keep connections up, spinning their wheels on every open folder. That uses up valuable threads in java (one thread per connection I believe), which could quickly exhaust your resources. 

But this is mostly speculation on my part right now, because we haven't actually hit Zimbra with hundreds of IMAP connections to see how well it performs..

-- 
Steve Hillman                                IT Architect
hillman@sfu.ca                               IT Infrastructure
778-782-3960                                 Simon Fraser University
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