SonicWall Email Security Appliances:3300, 4300, 8300, 5000, 7000, 9000, ES VA. Firmware/Software Version: 9.1.3 and above
The new SMTP authentication support for Email Security 9.1.3 and above can be used to protect the customer’s infrastructure from unauthorized use. For example, requiring a user to authenticate before sending outbound email can prevent an open relay.
To configure SMTP Authentication for Outbound, follow these steps:
Navigate to Manage > Network > Server Configuration page.
Under Outbound Email Flow, click on Add Path, if you have a path already configured then click on the path and edit the path
Scroll down to the Advanced Settings section
Under Use this text instead of a host name in the SMTP banner, enter a hostname. This is optional
Under Reserve the following port, enter a port number or keep the default port number
Enable the check box under Enable StartTLS on this path.
Click on Configure Authentication
On the next page, select the radio button under This path uses credential as follows.
Enable the check box Sends an SMTP AUTH command with the following credentials to the downstream mail server.
Under Require encrypted connectsion for authentication (SMTP AUTH) commands, enable the check boxes under Upstream Connections and Downstream connections.
Click on Apply to save the changes.
NOTE:Authentication does not protect the contents of the email. Therefore, TLS must be enabled as well so that the credentials passed on to the authenticating host are leveraging TLS encryption. This ensures that the SMTP Auth credentials are not passed over in the clear.