> >Check out DnsQuery component, I think that's what you need.
> Can it be done and how ?
This is a very simple MX lookup I wrote a long time ago, it fills two
arrays with a list of SMTP servers for the domain and their priority,
you are supposed to try the lowest numbered preference server first,
then in increasing number if refused. sysdelay can be replaced by
Application.ProcessMessages and GetTickCount for create the two second
delay.
Angus
// DNS commons vars
ServersTotal: integer = 0 ;
ServersList: array [1..9] of string ;
ServersPref: array [1..9] of integer ;
DNSReqId: integer ;
function TMainForm.GetMXServerName (email: string): boolean ;
var
count, retries: integer ;
domain: string ;
begin
result := true ;
ServersTotal := 0 ;
for count := 1 to High (ServersList) do ServersList [count] := '' ;
// get domain from email address
count := pos ('@', email) ;
if count = 0 then exit ;
domain := copy (email, count + 1, 88) ;
// set DNS server address - should really get whatver windows is using
DnsQuery.Addr := DNSServer.Text ;
for retries := 1 to 4 do // UDP may ignore request
begin
DNSReqId := DnsQuery.MXLookup (domain) ;
for count := 1 to 40 do // wait two seconds
begin
if ServersTotal <> 0 then
begin
if ServersTotal < 10 then result := false ;
exit ; // completed
end ;
sysDelay (50) ;
end ;
end ;
end;
procedure TMainForm.DnsQueryRequestDone(Sender: TObject; Error: Word);
var
I : Integer;
nIndex : Integer;
begin
ServersTotal := 0 ;
if DNSReqId <> DnsQuery.ResponseID then
begin
Error := 9999 ;
end ;
if Error = 0 then
begin
for I := 0 to DnsQuery.ResponseANCount - 1 do
begin
nIndex := DnsQuery.AnswerTag [I];
if (nIndex >= 0) and
(DnsQuery.AnswerType [I] = DnsQueryMX) then
begin
inc (ServersTotal) ;
ServersPref [ServersTotal] :=
DnsQuery.MXPreference [nIndex] ;
ServersList [ServersTotal] :=
DnsQuery.MXExchange [nIndex] ;
end;
end ;
end ;
if ServersTotal = 0 then ServersTotal := 99 ; // error
end;
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