I implemented zimbra into our company last year sometime(120 users). All has been running fine barring this problem that has just surfaced.
One user(outlook 2007) is able to send and receive email no problem throughout the day and then every now again it stops working at different times and periods of the day. The funny thing is that the the connector and outlook dont report any errors or failures, but If i login via the web interface there are emails sitting on the server. The only way I get the mail to download/sync from the server again is to close outlook and reopen it again.