About the advantages of Symantec Message Filter deployment at the gateway level
Following are the advantages when you deploy Symantec Message Filter at the gateway level:
Detects spam at the point of entry
Because spam originates from the outside world, the gateway is the logical, effective place to deploy the server.
Saves the resources
When you deploy Symantec Message Filter closer to the gateway, you can minimize mail processing and storage requirements. Spam is removed from the email stream, which reduces network bandwidth.
Lets you enable the early verdict feature
When you deploy the product at the gateway, the Scanner can determine an early verdict on the IP address before the entire message is received. If the message is blocked, the MTA does not need to continue through the remainder of the calls, thereby reducing scanning resources.
See About Symantec Message Filter deployment at the gateway layer.