Affects outbound directory exchange and prevents users in the specified GroupWise domains from appearing in the Exchange Address Book when directory synchronization and exchange are enabled. Users from all unlisted domains are allowed. See Section 8.1, Enabling Directory Synchronization and Exchange of Address Books.
See also /allowdom.
IMPORTANT:Do not use the /allowdom and /blockdom switches together. If both are specified, only the /allowdom switch takes effect.