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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
mailman: HCkMailMan;
email: HCkEmail;
success: Boolean;
badAddrs: HCkStringArray;
i: Integer;

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

mailman := CkMailMan_Create();

// SMTP connection settings...
CkMailMan_putSmtpHost(mailman,'smtp.example.com');
CkMailMan_putSmtpUsername(mailman,'MY_SMTP_USERNAME');
CkMailMan_putSmtpPassword(mailman,'MY_SMTP_PASSWORD');
CkMailMan_putSmtpSsl(mailman,True);
CkMailMan_putSmtpPort(mailman,465);

// Create a new email object
email := CkEmail_Create();

CkEmail_putSubject(email,'This is a test');
CkEmail_putBody(email,'This is a test');
CkEmail_putFrom(email,'myemail@example.com');
success := CkEmail_AddTo(email,'person1','person1@example.com');
success := CkEmail_AddTo(email,'person2','person2@example.com');
success := CkEmail_AddTo(email,'person3','person3@example.com');
// The SMTP server smtp.example.com won't know anything about an email address @somewhere_else.com
success := CkEmail_AddTo(email,'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 := CkStringArray_Create();
success := CkMailMan_VerifyRecips(mailman,email,badAddrs);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkMailMan__lastErrorText(mailman));
    Exit;
  end;

i := 0;
while i < CkStringArray_getCount(badAddrs) do
  begin
    Memo1.Lines.Add(CkStringArray__getString(badAddrs,i));
    i := i + 1;
  end;

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

CkMailMan_Dispose(mailman);
CkEmail_Dispose(email);
CkStringArray_Dispose(badAddrs);

end;