PE wrote:

I have created rules to permanently delete some of the incoming junk
mail but they do not always work and the mail finishes up in the junk
mail folder.

That's because the Junk E-mail filter runs before your rules do. That's by
design so that if you have rules that move messages to other folders, they
won't move junk.

Is it possible to create a macro (or another rule) which would run the
rule(s) to delete these messages once they are in the junk folder in
plain text? If so, I would appreciate your help in creating one as I
have no experience of writing a macro.

Someone else will have to comment.
--
Brian Tillman