I am using Zimbra Network 4.0.3 on Redhat ES 4. Since I needed to replace my dying cell phone, I purchased the Nokia E62. Here are my observations. The bottom line is .... this is way kool.
1) I have been unable to sync using a secure connection. I noted in another thread the method of adding the self-signed certificate for Zimbra. Despite this, all attempts to secure sync cause a hang requiring a reboot of the E62 to regain normal sync functioning.
2) Placing tags on contacts in Zimbra makes the contact unusable on the E62. The contact is synced but it is titled (unnamed). Editing the contact on the E62 shows "no data". If I remove the tags on Zimbra, the contacts are once again fully usable.
3) "Always On" syncing is not enabled by Mail for Exchange. It is an option for syncing but you will receive an error message if you use it. The next fastest time is 15 minutes.
4) On calendar events, you can replace (but NOT edit) the note field. So if you add "This note written using Zimbra" under Zimbra in the note field of a calendar event, you can read this note. But, you can not ADD the line "And this note added using E62". You would instead have to replace the Zimbra note with the E62 note.
5) I have been unable to figure out how to sync anything but the Inbox of Zimbra. I have emails that are important but I do not want them "clogging" up my Inbox. So, I always create a "Save" folder (in Zimbra). Important message go to Save. I made the Save folder as a separate folder at first to see if I could include it in the sync process... without luck. I then moved the Save folder (in Zimbra) to be a subfolder of the Inbox. This subfolder does not show up on the E62.
So, how well does it really work? Pretty darn well. Every 15 minutes the E62 syncs with Zimbra. If I have an email, I hear a lite musical tone plus there is a blinky light that goes off. I press a button and I can read the emails. The calendar events are all synced, as well as the contacts (personal contacts only). I can add,delete and edit email, calendar and contacts on Zimbra <--> E62.
You can send email from the E62 using the "keyboard". You will not be a speed typist with this keyboard but it does work for short emails... which is all I would want to send with a "phone" device.
This phone plus Network Zimbra is great!