Pascal (Lazarus/Delphi)

OAuth2 for a GMail using a P12 Service Account Key

See more GMail REST API Examples

Demonstrates how to use GMail with OAuth2 for a service account within a Google Workspace Account where your email domain is custom (e.g., @yourcompany.com).

Note: This example does not work for Personal Google Accounts where the email domain is @gmail.com

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Http,
  Chilkat.Email,
  Chilkat.Cert,
  Chilkat.MailMan;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  http: THttp;
  cert: TCert;
  iss: string;
  scope: string;
  oauth_sub: string;
  numSec: Integer;
  accessToken: string;
  mailman: TMailMan;
  email: TEmail;

begin
  success := False;

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

  http := THttp.Create;

  //  --------------------------------------------------------------------------------
  //  For a step-by-step guide for setting up your Google Workspace service account,
  //  see Setup Google Workspace Account for Sending SMTP GMail from a Service Account
  //  --------------------------------------------------------------------------------
  //  Begin by loading your Google service account key (.p12)
  cert := TCert.Create;
  success := cert.LoadPfxFile('c:/someDirectory/keys/chilkat25-cbd7b42afbd8.p12','notasecret');
  if (success <> True) then
    begin
      WriteLn(cert.LastErrorText);
      Exit;
    end;

  //  The ISS is your service account email address ending in gserviceaccount.com.
  iss := 'chilkatsvc@chilkat25.iam.gserviceaccount.com';

  //  The scope is always the following string:
  scope := 'https://mail.google.com/';

  //  The sub is your company email address
  oauth_sub := 'bob@yourcompany.com';

  //  The access token is valid for this number of seconds.
  numSec := 3600;

  accessToken := http.G_SvcOauthAccessToken(iss,scope,oauth_sub,numSec,cert);
  if (http.LastMethodSuccess <> True) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end
  else
    begin
      WriteLn('access token: ' + accessToken);
    end;

  //  The access token allows us to send unlimited emails while it's valid. Once it expires, we must obtain and use a new one.

  //  -----------------------------------------------------------------------
  mailman := TMailMan.Create;

  //  Set the properties for the GMail SMTP server:
  mailman.SmtpHost := 'smtp.gmail.com';
  mailman.SmtpPort := 587;
  mailman.StartTLS := True;

  mailman.SmtpUsername := 'bob@yourcompany.com';
  mailman.OAuth2AccessToken := accessToken;

  //  Create a new email object
  email := TEmail.Create;

  email.Subject := 'This is a test';
  email.Body := 'This is a test';
  email.From := 'Bob <bob@yourcompany.com>';
  success := email.AddTo('Recipient','recipient@example.com');
  //  To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

  success := mailman.SendEmail(email);
  if (success <> True) then
    begin
      WriteLn(mailman.LastErrorText);
      Exit;
    end;

  success := mailman.CloseSmtpConnection();
  if (success <> True) then
    begin
      WriteLn('Connection to SMTP server not closed cleanly.');
    end;

  WriteLn('Successfully sent email using Gmail with a service account key.');


  http.Free;
  cert.Free;
  mailman.Free;
  email.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.