I have a mixed Exchange environment with Exchange 2007 SP3 & 2010 CAS servers. For now, I already built a connection with MFG and organization relationships with my partner.
The issue is when I try to select specific several mailboxes in the sharing policies, there is no Exchange 2007 mailbox in the list.
From my research, the federated calendar sharing can support mixed Exchange Environment. I cannot figure out the root cause, please help.