(Delphi ActiveX) Verify Email Recipients

A way to possibly determine valid/invalid email addresses. I would recommend being very careful about doing this because your IP address may be flagged as a potential spammer by the mail server (because you are probing for valid/invalid email addresses). This Chilkat functionality existed for many years, before this kind of activity became a problem. The functionality remains only because it is useful for some to test with their own SMTP servers.

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
mailman: TChilkatMailMan;
email: TChilkatEmail;
success: Integer;
badAddrs: TCkStringArray;
i: Integer;

begin
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

mailman := TChilkatMailMan.Create(Self);

// SMTP connection settings...
mailman.SmtpHost := 'smtp.example.com';
mailman.SmtpUsername := 'MY_SMTP_USERNAME';
mailman.SmtpPassword := 'MY_SMTP_PASSWORD';
mailman.SmtpSsl := 1;
mailman.SmtpPort := 465;

// Create a new email object
email := TChilkatEmail.Create(Self);

email.Subject := 'This is a test';
email.Body := 'This is a test';
email.From := 'myemail@example.com';
success := email.AddTo('person1','person1@example.com');
success := email.AddTo('person2','person2@example.com');
success := email.AddTo('person3','person3@example.com');
// The SMTP server smtp.example.com won't know anything about an email address @somewhere_else.com
success := email.AddTo('person3','person4@somewhere_else.com');
// ...

// Verify recipients.
// **** See the warning about using this API method in the description above.
// (An SMTP server only knows valid email address for its own domain.  For example,
// smtp.example.com *may* only know if person1@example.com is valid or invalid, but does
// not know anything about the validity of email addresses having other domains.)
badAddrs := TCkStringArray.Create(Self);
success := mailman.VerifyRecips(email.ControlInterface,badAddrs.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(mailman.LastErrorText);
    Exit;
  end;

i := 0;
while i < badAddrs.Count do
  begin
    Memo1.Lines.Add(badAddrs.GetString(i));
    i := i + 1;
  end;

Memo1.Lines.Add('done.');
end;