performance/bw requirements for disconnected imap?

[deploylinux]

Hello,
We started using/recommending disconnected imap to our zimbra users w/ newer email clients several months ago and overall it has been a good experience. Unfortunately, we're now starting to see relatively large increases in bandwidth usage as a result (some users are using a constant 2-4GB/HR) and this is when they are not at their desk and leaving the email client open. One would think that the imap protocol would be smart enough to just check for changes and forward changes to the client, but this does not seem to be the case ...at least for some clients (I'm not really sure whether the complete imap store is being downloaded for each user hourly or not). I would assume this is a known issue - assuming that disconnected imap is here to stay, how are other admins/networks dealing w/ this?
Thanks,
Matt

[phoenix]

Originally Posted by deploylinux

We started using/recommending disconnected imap to our zimbra users w/ newer email clients several months ago and overall it has been a good experience. Unfortunately, we're now starting to see relatively large increases in bandwidth usage as a result (some users are using a constant 2-4GB/HR) and this is when they are not at their desk and leaving the email client open.

I assume that by 'disconnected IMAP' you mean IMAP IDLE? If you do then I see no reason why you would see that amount of traffic by leaving a mail client open all the time. I leave several IMAP clients open and connected to my own server and none of those show much traffic between them and the server. How are you measuring the traffic? Are you actualy sure it's their mail client that's originating the traffic? Have you tried an alternative client such as Zimbra Desktop to rule out client problems?

You don't mention which version of Zimbra is in use, you should update your forum profile with the output of the following command (do not post the output in this thread):

zmcontrol -v

[deploylinux]

Originally Posted by phoenix

I assume that by 'disconnected IMAP' you mean IMAP IDLE? If you do then I see no reason why you would see that amount of traffic by leaving a mail client open all the time. I leave several IMAP clients open and connected to my own server and none of those show much traffic between them and the server. How are you measuring the traffic? Are you actualy sure it's their mail client that's originating the traffic? Have you tried an alternative client such as Zimbra Desktop to rule out client problems?

Yes, one would think that imap idle would solve the b/w issues w/ disconnected imap, but I haven't really investigated enough on if disconnected imap implementations on other clients do anything above/beyond standard imap except for keeping a local copy of any email downloaded and doing a full download on the first connect. I'm sure there is some additional synchronization on the first connect after the client is started also - but I'm wondering if that sync is being performed on each check rather than just using imap idle.

I've heard several complaints on this, and have started to review it - we're certainly seeing it in our bandwidth charts.

Basic test here on a mailbox w/ ~1GB email showed that there each mailbox interval update via kde kmail 4.4 took ~40 seconds over a 3Mbps bonded t-1 to datacenter. I will start testing other clients.

You don't mention which version of Zimbra is in use, you should update your forum profile with the output of the following command (do not post the output in this thread):

zmcontrol -v

done.

[deploylinux]

ah, perhaps our company is seeing this because we're a linux consulting company and have a large number of users w/ linux mail clients and apparently many of the upstream projects are just now releasing or including IDLE support - in particular, kmail 4.4 does not include it although it appears kmail 4.6 w/ akonadi may.

https://bugs.kde.org/show_bug.cgi?id=67504

[phoenix]

Originally Posted by deploylinux

ah, perhaps our company is seeing this because we're a linux consulting company and have a large number of users w/ linux mail clients and apparently many of the upstream projects are just now releasing or including IDLE support - in particular, kmail 4.4 does not include it although it appears kmail 4.6 w/ akonadi may.

The amount of bandwidth consumed would lead me to believe this is purely an IMAP client problem. You can check it with something like Thunderbird (or Zimbra Desktop via an IMAP connection), after the initial sync there should be almost no bandwidth used by the client.