Add the following line to your local hosts file located at C:\Windows\System32\Drivers\etc:

133.0.0.1 MAILS-BEST-FRIEND.keysvr.declude.com

Next, open the declude.cfg file located inside of the Declude directory.  You will see a line that says.. CODE [Imail enter your code, Smartermail delete this line etc..]. Delete the brackets and everything inside the brackets and add MAILS-BEST-FRIEND. The line should look just like this:

CODE     MAILS-BEST-FRIEND

Close and save the file then delete your current diags.txt and restart your decludeproc service. A new diags.txt will be generated and the error will be gone.