imap server performance benchmarks

Jerome Herman jherman at
Fri Mar 9 03:09:16 UTC 2012

On 09/03/2012 03:44, Da Rock wrote:
> I'm reconsidering my current setup (postfix/courier) for imap and I 
> was doing some research on performance comparisons between imap server 
> setups. I stumbled on this article just just about fell of my chair 
> laughing when I read the last article on future benchmarking tests to 
> perform:
> Considering I have close to a hundred folders or more, and an average 
> of 50,000 emails in each (yes, not good, and I am working on archiving 
> but it won't help _that_ much) with nearly 200,000 in just one! I got 
> a real kick out of the comment that "no sane email user would have 
> more than 21,000 emails in a folder" - that would make me certifiable 
> :D Oh, and that most email wouldn't be more than a GB or so... mine's 
> edging 6GB already...
> So, all jokes aside, I contemplated that I would make an ideal test 
> case to the extreme for benchmarking imap servers. Anyone have any 
> suggestions on what to test/how? Anyone have some tools they have 
> created for a similar challenge? I have my own ideas, but if anyone 
> wants me to try something I'd be willing to give it a shot.
> If anyone has a better idea on which list this should be posted to as 
> well - I considered the lists available (I'm hooked up to most) and 
> couldn't see any better.
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No IMAP test is as vicious or as thorough as a real life company 
deciding to change its mail client from one day to the next and counting 
on IMAP to automagically restore local archives. If the company more or 
less uses IMAP folder as a share drives it is even better.
It happened to me once. Postfix/Dovecot did handle the change quite 
well, yet some mailboxes took days before the local copy was in sync 
with IMAP folders.
There was about 200GB of mail to download (35 users company) the load 
average was under 0.25 all the time on an i5 dual core with 8GB of ram.

Duplicating a mailbox X times and having X clients doing a local copy of 
the entire mailbox sounds like a good first test, with mailbox size and 
number X on par with what you expect to find on your network.

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