SUMMARY

 Which registry keys are effected when RDNS lookup options are performed.

DETAIL

MailEnable queries the registry to determine whether it should perform a spam database lookup for an inbound hosts IP Address. These options can be set via the Administration console, however this article outlines the relevant registry keys used. Reverse DNS Blacklisting does not work on Windows NT 4, and these keys should not be changed.

MORE INFORMATION

The following key is queried to determine whether or not RBL lookups are performed and whether they are performed when a mail server/client connects to the server or when the client specifies the recipients of a message. If you change settings in the administration program it may revert this value from 2 to either 1 or 0, since option 2 is not configurable through the interface.

For 64bit Windows

Key Name: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Mail Enable\Mail Enable\Connectors\SMTP\Reverse DNS Blacklist

For 32bit Windows

Key Name: HKEY_LOCAL_MACHINE\SOFTWARE\Mail Enable\Mail Enable\Connectors\SMTP\Reverse DNS Blacklist

Value Name: Enabled
Values: 1=Check RBL on Recipient command (RCPT) 
            2=Check RBL on Connection 
            0=Disabled

The next registry keys queried determines which registry key branches to check for the list of RBL Provides. This contains a comma delimited list of the registry subkeys that need to be enumerated to determine which hosts are active.

Key Name: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Mail Enable\Mail Enable\Connectors\SMTP\Reverse DNS Blacklist
Value Name: Processing Order
Default Value:BarracudaBRBL,Spamcop,SpamhausZEN

Finally, MailEnable then checks all the subkeys contained in the above registry key and performs a reverse lookup against each provider that has its "Enabled" value set to 1.

How to configure Reverse DNS Blacklisting: http://www.mailenable.com/kb/content/article.asp?ID=ME020162

How to create and manage your own RDNS Blacklist Server: http://www.mailenable.com/kb/content/article.asp?ID=ME020271

Why is Reverse DNS Blacklisting not available on Windows NT 4.0?: http://www.mailenable.com/kb/content/article.asp?ID=ME020161

Which Registry Keys are used when performing Reverse DNS Lookups?: http://www.mailenable.com/kb/content/article.asp?ID=ME020127

How to get tough on spam/Blacklisting: http://www.mailenable.com/kb/content/article.asp?ID=ME020084