fn is_protected(key: &str) -> boolExpand description
Returns whether the outer header value must be ignored if the message contains a signed (and optionally encrypted) part. This is independent from the modern Header Protection defined in https://www.rfc-editor.org/rfc/rfc9788.html.
NB: There are known cases when Subject and List-ID only appear in the outer headers of signed-only messages. Such messages are shown as unencrypted anyway.