rem: if ( mParameter.isEmpty() ) return ErrorButGoOn; msg->setHeaderField( "X-KMail-Transport", mParameter );
add: int idx = mParameterList.findIndex( mParameter ); if ( idx < 1 ) return ErrorButGoOn;  if ( idx == 1 ) msg->setMDNSentState( KMMsgMDNIgnore ); else sendMDN( msg, mdns[idx-2] );
context: KMFilterAction::ReturnCode KMFilterActionTransport::process(KMMessage* msg) const{  if ( mParameter.isEmpty() )    return ErrorButGoOn;  msg->setHeaderField( "X-KMail-Transport", mParameter );  return GoOn;}