procedure TForm1.btnSendSignedClick(Sender: TObject);
begin
  //composing a new message
  clSMimeMessage1.BuildMessage('The message text...', 'HTML content...');
  clSMimeMessage1.Subject := 'Subject line follows here';
  clSMimeMessage1.From.FullAddress := 'sender@domain.com';
  clSMimeMessage1.ToList.Clear();
  clSMimeMessage1.ToList.Add('recipient@another.com');

  //configuring the signature parameters
  clSMimeMessage1.Config.SignAlgorithm := szOID_NIST_sha512;
  clSMimeMessage1.Config.SMimeVersion := clSMime32;

  //signing the message
  clSMimeMessage1.Sign();

  //configuring the SMTP connection
  clSmtp1.Server := 'smtp.mailhost.com';
  clSmtp1.UserName := 'sender@domain.com';
  clSmtp1.Password := 'secret';

  //sending the message
  clSmtp1.Open();
  clSmtp1.Send(clSMimeMessage1);
  clSmtp1.Close();
end;

procedure TForm1.btnSendEncryptedClick(Sender: TObject);
begin
  //composing a new message
  clSMimeMessage1.BuildMessage('The message text...', 'HTML content...');
  clSMimeMessage1.Subject := 'Subject line follows here';
  clSMimeMessage1.From.FullAddress := 'sender@domain.com';
  clSMimeMessage1.ToList.Clear();
  clSMimeMessage1.ToList.Add('recipient@another.com');

  //configuring the encryption parameters
  clSMimeMessage1.Config.EncryptAlgorithm := szOID_NIST_AES256_CBC;
  clSMimeMessage1.Config.SMimeVersion := clSMime32;

  //encrypting the message
  clSMimeMessage1.Encrypt();

  //configuring the SMTP connection
  clSmtp1.Server := 'smtp.mailhost.com';
  clSmtp1.UserName := 'sender@domain.com';
  clSmtp1.Password := 'secret';

  //sending the message
  clSmtp1.Open();
  clSmtp1.Send(clSMimeMessage1);
  clSmtp1.Close();
end;

procedure TForm1.clSMimeMessage1GetEncryptionCertificate(Sender: TObject;
  var ACertificate: TclCertificate; AExtraCerts: TclCertificateList;
  var Handled: Boolean);
begin
  //loading the encryption certificate -
  //the public-key certificate that belongs to the message recipient
  ACertificate := clCertificateStore1.CertificateByEmail('recipient@another.com');
  Handled := True;
end;

procedure TForm1.clSMimeMessage1GetSigningCertificate(Sender: TObject;
  var ACertificate: TclCertificate; AExtraCerts: TclCertificateList;
  var Handled: Boolean);
begin
  //loading the signing certificate -
  //the private-key certificate that belongs to the message sender
  ACertificate := clCertificateStore1.CertificateByEmail('sender@domain.com');
  Handled := True;
end;