What is pre-tested spam and how to stop it
By definition, a spammer pre-tests their campaign against all available anti-spam tests by sending samples to themselves on protected systems. When they have a version that gets past all of the tests they fire it off in huge volumes with their bot-net. As much as possible we stay ahead of them by predicting what their next rounds are likely to be and often that works, but if they manage to pre-test against us then they beat that also.
There are a few free solutions that we offer to combat pre-tested spam:
PRE-TESTED filter: Available for download here
Gauntlet: Available for download here
If the free solutions aren't enough, there are also a few paid solutions:
Run a DNS server on your Mail Server. This will provide you with 2 benefits. Better results as you can control the cache and faster response time. We suggest SimpleDNS We can help you get it setup if you like.
The other solution we have would be to implement a private RBL called SPAMZONES which specifically deals with pre-tested spam. If you are interested, please contact us for pricing.