If the number next to the Drafts folder is not the same as the number of messages in that folder, Thunderbird has failed to clean up its Deleted messages. Either "Empty Trash" in the Zimbra web client (which also cleans up after Thunderbird for this very reason) or do what lcxe says:[QUOTE...

The count next to the Drafts folder is the number of drafts, not the number of unread messages.

If you have features that you'd like to see added, please head over to bugzilla. Seriously. That is one of the main inputs we use in prioritizing what gets addressed when. Vote for the enhancements and bugs that you'd like to see us work on. Open new bugs if you can't find one that match...

Not yet. Like GMail, we support only subject-based threading at present.

Kinda depends how Outlook is storing those colored flags on your current IMAP server. If Outlook just uses Flagged and only stores the colors locally in the PST on the user's laptop, there's no way for imapsync to know about the colors and hence they wouldn't be migrated...

We use subject-based threading. For replies with no subject (e.g. "RE:"), Zimbra Desktop sees that the messages have the same normalized subject and assumes that they're in the same thread.

Use SoapProvisioning and ZMailbox instead of crafting the requests/responses yourself and using SoapHttpTransport.

Looks like you're missing a library. Add dom4j-1.5.jar to your Java classpath and try again.

There might be a few issues with "Show Original" fetch since the blob size in the database would no longer equal the actual blob size in the store.

That allows the "+whatever" to be ignored during delivery, but it doesn't enable selection of a target folder. That's Bug 9662 – Implicit folder delivery via LMTP plus address.