I've been running Zimbra in my office for some time now, and one day, a couple of months ago, I saw that emails had stopped downloading via IMAP.

This is the error message I'm getting now:

system failure: Unable to connect to IMAP server: DataSource: { id=........
Outlook is having no issues accessing the exact same account. I can even access another account through Zimbra using the exact same settings.

The error message begins with a "Unable to connect" line. It also says something about a Java certificate. Is there a chance that this certificate is being stored in a cache somewhere, needing to be refreshed?

Any help is appreciated.