Regular Expression as a filter

[vbell]

I want to use a regular expression to filter on a given number of instances of the string "PROSPECTS INFORMATION."

For example: I want the responder filter to produce a true condition output for every email that has exactly 3 occurances of the string "PROSPECTS INFORMATION", and produce a false output for any lesser or greater number of occurances of that string.

There can be a varying number of words that separate the occurances of "PROSPECTS INFORMATION". The best I've been able to produce up to now is an => number of instances true output.

Does anyone have a solution for this problem?