Ed W wrote:
Andrew Von Cid wrote:
Hi all,
I keep on hitting this problem when migrating new clients from POP or local IMAP servers (hosted on their LAN's) to my Dovecot setup, which is hosted properly in a data center. People usually complain that it's slower and although they're getting a kick ass mail setup it doesn't look good from their point of view.
I'm wondering if there is anything I could do to speed it up on their LAN's. What I mean is probably a caching IMAP proxy or some sort of replication to a local Dovecot server. Is this something Dovecot can do? I'd be really grateful for any opinions on how to tackle this problem.
My experience is that most mail clients drag down a LOT of data when you open a folder, hence the bandwidth required is surprisingly large. I also noticed that this data compresses EXTREMELY well. So my company just happens to make a compression proxy for use on seriously slow dialup links (2.4Kbit), but my own experience is that this speeds things up by around a factor of 2 on a typical fast broadband link (compared using Thunderbird)
There are various simple ways to test this thesis on your own setup, including a simple straight through proxy in about 20 lines or perl.
However, not sure what the best fix is for this problem?There was some discussion a few weeks back that SSL can have a compression layer turned on - Timo pointed out that this was disabled in both Dovecot and also TB. It might be possible to send Timo some money and have it enabled in Dovecot (looked like a very trivial one line fix?) - you could then (fix and) use ssltunnel to get the benefit whilst waiting for your patch to TB to be accepted into mainstream (or if it suits your userbase you could fix the code and distribute a changed version locally? If using Outlook then obviously this isn't possible, but no idea if Outlook already supports compressed SSL?)
You could also pay Timo to add support for the compressed IMAP protocol extension, but again you run into the problem that few/no clients support it (at least you have half the problem licked though)
Timo is also working on a very clever multi-master imap server replication engine - again probably tipping a few euros his way might speed up that process. This would give you a local cache server
Hope those ideas get you started?
Good luck
Ed W
A few IMAP client based things that seem to help are: disable all of the languages you don't need in Thunderbird; configure AppleMail to download only the messages you've read; configure Outlook/Outlook Express to sync at a more reasonable level to limit it from downloading everything every time; or make everyone use mutt/pine. The last isn't realistic but if mutt or pine works fine, then you know some client optimizations will help.
Webmail, as long as it isn't loaded with too much graphics, might work better with slow connections. For people connecting to Email while in a Rain Forest, POP seems to be the best option.
It also seems to me that fts plugin (free text indexing) improves performance. This might just be wishful thinking on my part.
Hope this helps a little.
---Jack