The IMP filter is plugin for the anti-spam software Spamihilator:
With the IMP filter (individual mail parsing filter) e-mails are analyzed to judge whether they is spam or not. The criteria of this classification aren't fixed. The user has to create his own individual TextTransformer project for this purpose.
For the construction of such projects the free version of the TextTransformer program suffices. Texts can be analyzed almost arbitrarily exactly with such projects. The effort for the making such projects is only worthwhile perhaps, though, when the statistical results of the word filters are too unsure and a certain result for special cases is needed.