Outlook Connector vs. IMAP

[Labsy]

Hi,

I run 100+ domains on ZCS server and it's running fine. Only problems I have are users with mailboxes over 2 GB in size which are using Outlook via IMAP. Problems involve several Outlook timeouts, neverending syncing, very slow changing view from one folder to another etc.

It is very hard to determine the REAL cause of al causes, which could be guilty for all problems, and it seems it's connectivity in general in one case, and too large mailbox in another case, then Outlook 2003 in third case...and so on.
But all problems have Outlook of any version in common.

So I am thinking about trying with Outlook connector. But since it's production server, I'd like to hear what experienced users and admins have to say about Outlook Connector:
- performace vise, how is it compared to IMAP? Faster, better?
- regarding endless sync problems with IMAP, is Outlook Connector designed better, for example to not sync everything all the time, or to optimise syncing in order to not cause problems with multi GigaByte mailboxes?

Thanx.

[Labsy]

Why am I asking this?
Because I found an article explaining IMAP over SSL communication, which seems quite concerning to me:

"...SSL code outside imap uses a memory buffer, which gets increased upon reading of mails by 4096 bytes. This creates a huge load on the host imap runs on by copying the memory buffers for every 4096 byte step. This does not ocure on IMAP without SSL."

Now, as I told, most of my clients, which extensivelly use their mailboxes (like a filesystem, transfering 5-20 MB pictures and files) experience problems on Outlook, which is connected to Zimbra server via SSL+IMAP.
Maybe that would be explained with extract from article, mentioned above? Might it be SSL guilty?

That's why I ask ybout difference between IMAP and Outlook connector.

[Krishopper]

Did you read that text from the imapsync website?

[Labsy]

Yes, that's where I've got it from. I assume it relates to IMAP+SSL in general, not just to imapsync.
...or me be wrong?

[Krishopper]

Yeah, that really only applies to imapsync, or Perl scripts.

The way Zimbra deals with IMAP and SSL is significantly different. Of course SSL uses slightly more memory and CPU because of the computations it has to do, but imapsync is significantly worse at doing it than Zimbra out of the nature that it uses Perl and perl modules.

We force SSL on all POP3 and IMAP and don't see any performance degradations.

Also keep in mind that Zimbra uses the same SSL libraries to encrypt the traffic to the Outlook connector - so it really woudln't be any more additional overhead than if you were using that.

In short: I wouldn't worry about it. imapsync has its own shortcomings, and that is one of them.

[xeon]

What version of Outlook are your clients using?

[Labsy]

Krishopper, thanx for explanation. Most probably I'll need to test Outlook connector one day.

Originally Posted by xeon

What version of Outlook are your clients using?

Xeon, our clients mostly use Outlook 2007 and 2010, with default send/receive schedule settings.

On my testing computer I configured 5 IMAP accounts, all with 3000+ mail messages each of total mailbox size of approx. 4 GB. Outlook practically did not get out of "Not responding" state.
Then I tested it with Mozilla Thunderbird, which also did not finish syncing even after few days.
In both scenarios Zimbra server was in datacenter with 600 Mbps throughput, and client was on 100 Mbps optical line.

Ok, that was extreme test, but proved to me that limits are not so far from present situation. Today's users have yearly mail traffic up to 5 GB and that's what concerns me. We sold them Office 2010 this year, and 1 year later their Outlook won't be suficcient anymore?

Zimbra Desktop is, with all regards and respect to developers, unfortunatelly not the product for Outlook-used-to users due to lack of Office integration features, mostly copy-paste support.

On the other side there is Outlook connector for Zimbra, but I am very sceptical due to very bad experience with Outlook on IMAP/SSL. Beside that, it's not so easy to test - as our zimbra is in production, I cannot configure just Outlook connector for testing, but I need to upgrade the whole server to trial version - not what I'd like to do.

So question remains - does Outlook connector wipe off all IMAP/SSL sync problems?

[xeon]

Originally Posted by Labsy

So question remains - does Outlook connector wipe off all IMAP/SSL sync problems?

The Outlook connector communicates to Zimbra server just like the web client does over SOAP API, I believe. So it is not using IMAP. Once the initial sync is done only updates are transmitted. I have zero issues with mailboxes 15GB+ and over 100k of messages. Even over a T1 (1.544Mbps) when they are out of the office they see no issues. I only communicate with my server over SSL using a GoDaddy SSL certificate.