This format matches all the subdomains under the example.com domain, for example, a.example.com, a.b.example.com.
The domains in the exception list must be subdomains of the blocked PTR domain. Trend Micro Email Security does not block messages from these subdomains.
To delete an exception, select the exception item and click Delete.
The blocked PTR domain appears in the blocked PTR domain list.
To remove a blocked PTR domain, select a PTR domain and click Delete. You can also select the checkbox in the table heading row to select all rules.