When collection is populated by AD Group (Add Groups .... ) and Preview button is clicked the following message is displayed:
"Cannot find any objects that can be added to the mailbox collection"
Please ensure the following conditions are true:
1. AD group is mail-enabled.
2. AD group type is defined as Distribution.
When "Preview" button is clicked LDAP request is sent to the source AD, attempting to resolve member attribute of DL. Since the console often resides on the target domain, name resolution or firewall can prevent LDAP requests. As troubleshooting suggestions the following steps are recommended:
1. ADInsight tool from Sysinternals can be used to monitor an outcome of LDAP traffic while "Preview" button is clicked. This can identify potential connectivity issues and tell what DC it's going to. Utility can be downloaded from the Microsoft TechNet pages:
2. LDP.EXE utility (part of Windows 2000/2003 Support Tools) can be used to verify LDAP connectivity to DC.