(Delphi DLL) Send DKIM Signed Email

Demonstrates how to create a simple email, add a DKIM signature, and send it.

Note: Requires version 9.0.3 or greater.

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, PrivateKey, CkByteData, Email, Dkim;

...

procedure TForm1.Button1Click(Sender: TObject);
var
mailman: HCkMailMan;
dkim: HCkDkim;
email: HCkEmail;
success: Boolean;
mimeData: HCkByteData;
password: PWideChar;
privKey: HCkPrivateKey;
dkimSignedMime: HCkByteData;
strFrom: PWideChar;
strTo: PWideChar;

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

// The mailman object is used for sending and receiving email.
mailman := CkMailMan_Create();

// The dkim object is used for creating the DKIM signature.
dkim := CkDkim_Create();

// Set the SMTP server.
CkMailMan_putSmtpHost(mailman,'smtp.chilkatsoft.com');

// Set the SMTP login/password (if required)
CkMailMan_putSmtpUsername(mailman,'myLogin');
CkMailMan_putSmtpPassword(mailman,'myPassword');
// Set the SmtpPort if your SMTP server uses an alternative port (default = 25)
CkMailMan_putSmtpPort(mailman,587);

// 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,'Chilkat Support <support@chilkatsoft.com>');
// We'll send the email to a Yahoo email account.  It is then
// possible to view the full headers within the Yahoo email
// interface to see if the DKIM signature was accepted.
success := CkEmail_AddTo(email,'Chilkat Software','chilkat_software@yahoo.com');
success := CkEmail_AddTo(email,'Chilkat Admin','admin@chilkatsoft.com');

// When sending an email with a DKIM signature, the MIME
// of the email must not be modified (in significant ways) prior to
// or during the sending process.  Therefore, the MIME of the
// email is assembled, the DKIM signature is added, and then
// SendMimeBytes is called to send the email.

// Get the MIME of the email.  Calling RenderToMimeBytes 
// causes the email to be signed and/or encrypted if those options
// have been selected.  The MIME returned by RenderToMimeBytes
// is the exact MIME that would've been sent if SendEmail was
// called.  We'll add a DKIM signature header to this MIME and then send...
mimeData := CkByteData_Create();
success := CkMailMan_RenderToMimeBytes(mailman,email,mimeData);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkMailMan__lastErrorText(mailman));
    Exit;
  end;

// To create a DKIM signature for email (i.e. MIME),
// you'll need to provide the following:
// (1) An RSA private key in any common file format.
// (2) The domain name (typically the same domain
// as the sender of an email).
// (3) A selector for the domain name -- an arbitrary string
// to identify the matching public key in DNS.

// To allow an email recipient to verify the DKIM signature via an
// external email client supporting DKIM or using other software,
// you will need to create a DNS record with the selector
// and matching public key.  This example does not provide
// information about DKIM DNS record creation.  
// (Chilkat does not provide an API for creating DNS records.  
// Creating the DKIM DNS record is something you would do
// manually.)

// Set the domain and selector:
// You'll need to provide your own values here..
CkDkim_putDkimDomain(dkim,'chilkatsoft.com');
CkDkim_putDkimSelector(dkim,'brisbane');

// Load a private key from any common RSA private key
// format, such as DER, PKCS8, PEM, XML, etc.
// The LoadDkimPkFile method automatically detects
// the file format and reads it appropriately.
// If a password is not required, you'll still need to provide
// a password string argument, but it is ignored.
password := 'optionalPassword';
privKey := CkPrivateKey_Create();
success := CkPrivateKey_LoadAnyFormatFile(privKey,'myPrivateKey.pem',password);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

success := CkDkim_SetDkimPrivateKey(dkim,privKey);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkDkim__lastErrorText(dkim));
    Exit;
  end;

// Add the DKIM-Signature header and
// returns the new MIME with DKIM-Signature added.
dkimSignedMime := CkByteData_Create();

success := CkDkim_AddDkimSignature(dkim,mimeData,dkimSignedMime);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkDkim__lastErrorText(dkim));
    Exit;
  end;

// Call SendMimeBytes to connect to the SMTP server and send.
// The connection (i.e. session) to the SMTP server remains
// open so that subsequent Send* calls may use the
// same connection.  
strFrom := 'support@chilkatsoft.com';
// To send to multiple email addresses, the strTo should be set to a comma-separated
// list of email addresses.
strTo := 'chilkat_software@yahoo.com, admin@chilkatsoft.com';
success := CkMailMan_SendMimeBytes(mailman,strFrom,strTo,dkimSignedMime);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkMailMan__lastErrorText(mailman));
    Exit;
  end;

// Some SMTP servers do not actually send the email until 
// the connection is closed.  In these cases, it is necessary to
// call CloseSmtpConnection for the mail to be  sent.  
// Most SMTP servers send the email immediately, and it is 
// not required to close the connection.  We'll close it here
// for the example:
success := CkMailMan_CloseSmtpConnection(mailman);
if (success <> True) then
  begin
    Memo1.Lines.Add('Connection to SMTP server not closed cleanly.');
  end;

Memo1.Lines.Add('DKIM Signed Mail Sent!');

CkMailMan_Dispose(mailman);
CkDkim_Dispose(dkim);
CkEmail_Dispose(email);
CkByteData_Dispose(mimeData);
CkPrivateKey_Dispose(privKey);
CkByteData_Dispose(dkimSignedMime);

end;