On Friday 16th December 2011 starting at 8pm GMT we will be restarting the Zimbra service. The restart should take no longer than 15 minutes. All incoming email will be queued, access to the Zimbra servers will be restricted and Zimbra customers will not be able to access their mailboxes.

The restart is required to apply a configuration change which will remove the X-Originating-IP header from all mail sent from Zimbra. This header is causing a couple of users internal mail to be marked as spam because they're sending mail from an IP address that's listed on an RBL.

Zimbra have the following open bug to fix this problem without requiring the header removal http://bugzilla.zimbra.com/show_bug.cgi?id=44384.