Sync 2 Accounts on 2 Zimbra Servers?

[izrunas]

How can I sync two user account calendars on two separate Zimbra servers in different domains? i.e., a user uses two separate Zimbra OSE servers and has two separate calendars that need bi-directional sync.

[izrunas]

Anyone have a solution on this? I use two separate Zimbra servers and need my calendars to match and update each other with busy times, etc. Thanks!