You might try asking the Zimbra Admin interface to re-index the user's account, too. Usually is someone complains about search not working the index has gotten corrupted.
Also, there is actually a feature in Zimbra that will delete old mail. If you look in the Class of Service settings in the Advanced tab there's a section near the bottom for Email Retention Policy. There's three categories, one for Email in general, one for Trash, and one for Junk. Trash and Junk both default to 30 days (if someone doesn't empty them in that long, it'll delete things on its own from those two folders). The "Email" one is the one that might be biting you here *if* that's what's happening. That one defaults to 0 ("keep everything"). If it's set to something other than zero that might be what you're hitting.
Also, I once had a user using Apple Mail to connect to Zimbra via IMAP and for some reason his client started deleting every message that came in as it came in. He never figured out why, and it stopped doing it when he restarted his Mac. |