Configuring Limits and Exceptions

Procedure

1. Go to Administration → Mail Settings → Limits and Exceptions.
2. Specify the Message Limits settings:

   Option	Description
   Maximum message size	Specify maximum message size from 1 to 2047 MB.
   Maximum number of recipients	Specify number of recipients from 1 to 99,999.

3. Specify the Relay Control options to filter incoming messages.

   Note Relay control settings only take effect when Deep Discovery Email Inspector is in MTA mode. When you enable the message rejection options, Deep Discovery Email Inspector matches the permitted sender list first and then checks for unknown recipients.

   • Reject messages from unknown sender domains: Select this option to block messages from senders with no matching domain through DNS lookup.
   • Reject messages from unknown sender IP addresses: Select this option to block messages from senders with no matching IP address through reverse DNS lookup.

     Note Enabling this feature blocks all messages from an edge MTA.

   • Reject messages to unknown recipients: Select this option to have Deep Discovery Email Inspector block messages with a sender not in the approved list and an unknown recipient. A recipient is considered as unknown if no result is found through LDAP query.

     Note If you enable this option, configure the permitted recipient domains. Otherwise, Deep Discovery Email Inspector will block the messages.

4. Specify the Permitted Recipient Domains.
   Do one of the following:

   • Add an single domain:
     1. Type a domain name.
     2. Click > to include the entry in the Permitted recipient domains list.
   • Import a list of domains:

     Note Deep Discovery Email Inspector can import domain names from a text file. Ensure that the text file contains only one email address per line.

     1. Click Import From File.
     2. Select a text file and click OK.
     The new entries appear in the Permitted recipient domains list.

   Note To export the permitted recipient domain list, click Export and save the text file on your computer. To replicate the same permitted recipient domain settings on several Deep Discovery Email Inspector appliances, import the text file on the target appliances. Deep Discovery Email Inspector bypasses SPF and DKIM verifications for domains you configure in the Permitted Recipient Domains list. For more information, see Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM).

5. Specify the Permitted Senders of Relayed Mail.
   • Deep Discovery Email Inspector only
   • Hosts in the same subnet
   • Hosts in the same address class

     Note When this option is selected, Deep Discovery Email Inspector will check if the IP address of Deep Discovery Email Inspector and hosts are in the same address class and subnet. Deep Discovery Email Inspector will only allow hosts to relay messages if they are in the same address class and subnet. For example: Class A: The Deep Discovery Email Inspector IP address is 10.1.2.3, and the hosts’ IP address is 10.1.2.x. Class B: The Deep Discovery Email Inspector IP address is 172.31.2.3, and the hosts’ IP address is 172.31.x.x. Class C: The Deep Discovery Email Inspector IP address is 192.168.10.3, and the hosts’ IP address is 192.168.10.x. Deep Discovery Email Inspector will not allow hosts to relay messages if they are in the same address class, but not in the same subnet. For example: Class A: The Deep Discovery Email Inspector IP address is 10.1.2.3, and the hosts’ IP address is 11.2.3.x. Class B: The Deep Discovery Email Inspector IP address is 172.31.2.3, and the hosts’ IP address is 172.32.x.x. Class C: The Deep Discovery Email Inspector IP address is 192.168.10.3, and the hosts’ IP address is 192.168.11.x.

   • Specified IP addresses

     Note Import settings from a file by clicking Import from a File. Export settings to a file by clicking Export.

6. Click Save.