function MXResolve(Domain: PChar): string;
var
pQueryResultsSet: PDNS_RECORDA;
Name: PChar;
begin
pQueryResultsSet := nil;
if DnsQuery_A(Domain, DNS_TYPE_MX, DNS_QUERY_STANDARD, nil, @pQueryResultsSet, nil) = 0 then
 begin
  Result:=pQueryResultsSet^.Data.MX.pNameExchange;
  GlobalFree(dword(pQueryResultsSet));
 end;
end;