In some cases, it is necessary to bypass the Symantec Global Bad Senders reputation list for an email source but the source is not fully trusted so spam scanning needs to performed for messages from that source. Adding the IP or network to the Local Good Sender IP list will exempt the email source from Symantec Global Bad Sender verdicts but has the addition effect of bypassing spam scanning.
Component : Messaging Gateway
Adding the IP or network to the Internal Mail Hosts list will cause all reputation scanning for the mail source, including connection classification, to be bypassed but all other applicable filtering modules will be applied to the message.
Administration > Configuration > host > Internal Mail Hosts
For more information on Internal Mail Hosts implications, see the following article: