PE wrote:

I have created a rule to delete any mail which contain certain
characters or words. This appears to work sometimes but some of the
mail containing these words still gets through (usually finish up in
the Junk mail folder). When I run the rule on the Junk Mail folder
these emails get deleted! So the rule would seem to be ok.

Any idea why the rule does not always work?

If your rule is examining HTML messages, it probably won't work.
--
Brian Tillman