Symantec Mail Security for Exchange (SMSMSE) is installed on Microsoft Exchange.  SMSMSE is configured to use the Premium Anti-Spam component. Some Spam missed by SMSMSE is marked as Spam by an RBL service provider using the source IP address. SMSMSE does not have an option to configure the use of an RBL service provider.

SMSMSE installed onto Exchange 2007/2010/2013 does not allow for the use of an RBL service provider.  See the following article: Heuristic Detection and Real-time Blacklist are no longer available as AntiSpam options after installing Symantec Mail Security for Microsoft Exchange (SMSMSE) on Exchange Server 2007/2010.

Use the Anti-Spam RBL feature of Microsoft Exchange Server.  See the following articles for suggestions on configuring Exchange  to use RBLs:

Configure IP Block List Providers Properties

 Examples of commands to add RBL's via the Exchange Management Shell:

• Add-IPBlockListProvider -Name bl.spamcop.net -LookupDomain bl.spamcop.net -Enabled $True -RejectionResponse "{1.EN_US} has blocked your IP address ({0.EN_US}) using the list '{2.EN_US}'. Please see http://www.spamcop.net/w3m?action=checkblock&ip={0.EN_US} for more information. This organization has no control over this RBL (Realtime Block List)."
• Add-IPBlockListProvider -Name dnsbl.sorbs.net -LookupDomain dnsbl.sorbs.net -Enabled $True -RejectionResponse "{1.EN_US} has blocked your IP address ({0.EN_US}) using the list '{2.EN_US}'. Please see http://www.au.sorbs.net/lookup.shtml for more information. This organization has no control over this RBL (Realtime Block List)."
• Add-IPBlockListProvider -Name zen.spamhaus.org -LookupDomain zen.spamhaus.org -Enabled $True -RejectionResponse "{1.EN_US} has blocked your IP address ({0.EN_US}) using the list '{2.EN_US}'. Please see http://www.spamhaus.org/query/bl?ip={0.EN_US} for more information. This organization has no control over this RBL (Realtime Block List)."