How do you activate "A custom action" in Rules

[Gregory V.]

Can the "A Custom Action" function be used to delete
outgoing mail that is being auto sent from my Contacts by
a Trojan that I am unable to remove from my computer?

If this is not a solution, is there a fix that I can use?
I have isolated the trigger incoming mail that causes
mail to go out.

 

[Jason K]

You can apply rules only after the mail has been sent. You would be better
off asking for help on fixing the problem, not treating the solution.