Domain Key Identified Mail (DKIM) is a protocol that uses public-key cryptography to allow the sending MTA to electronically sign legitimate email messages in a way that can be verified by recipient MTAs. Symantec Messaging Gateway can perform DKIM signing on outbound messages. This enables your recipients to identify messages as validly originating from you, and also to detect whether messages were modified after leaving your MTA. Symantec Messaging Gateway can also perform DKIM validation on inbound messages, to verify the authenticity of a DKIM signature and detect whether a message has been modified.
You implement DKIM signing on a per-domain basis. Symantec Messaging Gateway can add only one DKIM signature to an outbound message.
After enabling DKIM validation for all inbound messages, you can create a content filtering policy to choose the action that Symantec Messaging Gateway takes when an inbound message from a specific domain or group of domains fails DKIM validation. Symantec Messaging Gateway does not grant any type of enhanced processing to messages that pass DKIM validation.
Enabling DKIM validation may have an adverse affect on mail processing performance.
You can optionally modify the pre-configured policy for DKIM, then apply that policy to one or more policy groups. Optionally, you can limit the policy to specific recipient or sender domains, or change the action to take on these messages.