To allow Symantec Email Security to send emails on your behalf you will have to include it in your SPF record. The include statement used by Symantec Email Security that needs to be added in your DNS is:

include:spf.messagelabs.com

For more information please click on the button below.

Symantec Email Security can perform DKIM signing for outbound messages and DKIM validation on inbound messages. For information on how to configure both please click on the button below.

For information on DMARC and how to enable DMARC validation of inbound messages please click on the button below.

Create a free OnDMARC account to test your configuration.