Link 2 different zimbra's

[WhiteAngel]

I can't find an answer to my question.
2 sistercompanies have their own zimbra. I would like to know if it is possible to connect those two.
We could then share emaillists, contacts....

Actually... work like one zimbra but each zimbra has his own administrator and it's own domain.

[jholder]

In the Zimbra Network edition, you can link the two servers. You can also do some sort of LDAP auth link...but that would be useless