rem: KMFilterAction::ReturnCode KMFilterActionTransport::process(KMMessage* msg, bool& ) const
add: KMFilterAction::ReturnCode KMFilterActionBounce::process(KMMessage* msg, bool& ) const
context: KMFilterAction::ReturnCode KMFilterActionTransport::process(KMMessage* msg, bool& ) const{  if ( mParameter.isEmpty() )    return ErrorButGoOn;  msg->setHeaderField( "X-KMail-Transport", mParameter );  return GoOn;}