Control Network Traffic > Proxies > About the SMTP-Proxy

About the SMTP-Proxy

SMTP (Simple Mail Transport Protocol) is a protocol used to send email messages between email servers and also between email clients and email servers. It usually uses a TCP connection on Port 25. You can use the SMTP-proxy to control email messages and email content. The proxy scans SMTP messages for a number of filtered parameters, and compares them against the rules in the proxy configuration.

With an SMTP-proxy filter you can:

  • Adjust timeout, maximum email size, and line length limit to make sure the SMTP-proxy does not use too many network resources and can prevent some types of attacks.
  • Customize the deny message that users see when an email they try to receive is blocked.
  • Filter content embedded in email with MIME types and name patterns.
  • Limit the email addresses that email can be addressed to and automatically block email from specific senders.

To add the SMTP-proxy to your Firebox configuration, see Add a Proxy Policy to Your Configuration.

You can also configure subscription service settings for the SMTP-proxy. For more information, see:

Which Proxy Action To Use

When you configure a Proxy policy, you must select a Proxy Action appropriate to the policy. For a policy which allows connections from your internal clients to the internet, use the Client proxy action. For a policy which allows connections to your internal servers from the internet, use the Server proxy action.

In Fireware v11.9.3 and higher, the new default predefined proxy actions have "Standard" appended to the proxy action name. These settings are updated from previous defaults to reflect the latest Internet network traffic trends.

Configure the SMTP-Proxy

See Also

About Proxy Policies and ALGs

Configure the SMTP-Proxy to Quarantine Email

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