Header filter rules don't match RFC 2047 encoded headers
The match for a header filter rule is against the raw header. If the header is RFC 2047 encoded as binary or, at least in some cases, quoted printable, the match will likely fail.
The match for a header filter rule is against the raw header. If the header is RFC 2047 encoded as binary or, at least in some cases, quoted printable, the match will likely fail.