I am constantly presented with some issue, how I do block this or that? It seems that not many people know how to experiment so I will take a couple of examples for Merak Mail server as to how to stop the dynamically generated images and sources that seem to make it past some filters.

Ok so you can see we are using "regular expression" in the "body".

If you view the source of the email you will find a string that will put an end to these annoying emails one by one. Since they are the most offensive emails on the web and costing everyone in time and money.