Editing Network Policy Settings
Use the Security: Network Policies page to edit domain and email filter settings.
1. In the Embedded Web Server, click Properties > Apps > Email > Setup.
2. On the Email Setup page, click the Security tab.
3. For Network Policies, click Edit.
4. On the Security: Network Policies page, for Domain Filter Settings, select an option:
To have the printer ignore domains, click Off.
To allow access to addresses in selected domains or to restrict usage to approved domains only, click Allow Domains.
To block addresses in selected domains, click Block Domains.
5. For New Domain, type the domain that you want to add to the list, then click Add.
6. To remove a domain from the list, select a domain, then click Remove.
7. To allow LDAP email address searches without the @ symbol, for Allow LDAP Email Address without the @ Requirement, select On.
Note: 
Ensure that your mail server supports this requirement.
If you select On for Allow LDAP Email Address without the @ Requirement, the number of items returned by an LDAP search can increase.