Cut down on spam with IP Block List Providers (RBL)

One easy way to make a huge dent in the amount of spam your Exchange organization receives is to configure the IP Block List Providers anti-spam agent.  This component checks senders against known databases of spammers, infected computers and open relays.  Also known as real-time block lists (RBL), they are provided by a number of non-profit and for profit companies.  From my experience I like using the free block lists provided by:

• SpamHaus - zen.spamhaus.org
  
• SpamCop - bl.spamcop.net
• Surriel - psbl.surriel.com
• SORBS - dnsbl.sorbs.net

Adding the IP Block List provider to Exchange is very simple, just open up the Exchange Management Shell and run the command below:

Add-IPBlockListProvider -Name SpamHaus -LookupDomain zen.spamhaus.org -AnyMatch $True -Enabled $True -RejectionResponse “Your IP is on the spamhaus.org block list“

For other block list providers just modify the Name, LookupDomain and RejectionRespose.

After you add a IP block list provider you can run get-ipblocklistprovider to list all installed.  If you want to delete a provider run Remove-IPBlockListProvider -identity <name> and hit enter. 

Some IP Block List providers have test addresses that allow you to see if your block list is working.  For SpamHaus Zen just send an e-mail to nelson-sbl-test@crynwr.com and you will get the results back via e-mail in a few minutes.