gnus-posting styles no header in more specific case

Question

I would like to add specific custom header in more general match (e.g. "^comp.") and add no such custom header in more specific match (e.g. "^comp.mail."). How to do it?

Answer 1

This seems to be a good case for Gnus Posting Styles.

(
  ("^comp."
    ("X-Custom-Header" "Custom Stuff"))
  ("^comp.more.specific"
    ("X-Custom-Header" nil)))

If the value is nil the header will be removed. See one of the paragraphs in the huge wall of text that I linked above.