Configuring TLS Settings for Outgoing Messages

Procedure

1. Go to Administration → Mail Settings → TLS.
2. Click Outgoing Messages.
3. Do one of the following:
   • Click Add to create a new entry.
   • Click an entry.
4. Select a status option.
5. Specify the domain of target message recipients.

   Note You cannot change the domain setting for the default entry.

6. Select a security level.

   Security level	Description
   Never	Deep Discovery Email Inspector does not use TLS for the specified IP address or domain.
   Opportunistic	Deep Discovery Email Inspector declares support for TLS for the specified IP address or domain. The mail server can choose whether to start a TLS connection.
   Must	Deep Discovery Email Inspector requires TLS for communication for the specified IP address or domain. Communication between Deep Discovery Email Inspector and the mail server is encrypted.
   Verify	Deep Discovery Email Inspector requires the mail server to start a TLS connection for the specified IP address or domain. Deep Discovery Email Inspector sends its certificate to the mail server for client identification.
   DANE	Deep Discovery Email Inspector uses DANE for email message verification first. If DANE verification is unsuccessful, Deep Discovery Email Inspector performs one of the following based on the error condition: revert to using opportunistic TLS for secured connections, add the message to the deferred queue, or reject the message. For more information, see DANE for SMTP.
   DANE only	Deep Discovery Email Inspector uses DANE for email message verification. If DANE verification is unsuccessful, Deep Discovery Email Inspector adds the message to the deferred queue or rejects the message, depending on the error condition. For more information, see DANE for SMTP.

7. Select a cipher grade option.

   Note This field is not applicable if you select the Never security level.

   Cipher grade	Description
   Medium	Communication between Deep Discovery Email Inspector and SMTP servers uses "medium" and "strong" encryption cipher suites.
   High	Communication between Deep Discovery Email Inspector and SMTP servers uses "strong" encryption cipher suites.

8. Click Save.