(PHP Extension) OAuth2 for a GMail using a P12 Service Account Key

See more GMail REST API Examples

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

For more information, see https://www.chilkatsoft.com/google_workspace_setup_smtp_gmail.asp

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<?php

include("chilkat.php");

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

$http = new CkHttp();

// --------------------------------------------------------------------------------
// 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 = new CkCert();
$success = $cert->LoadPfxFile('c:/someDirectory/keys/chilkat25-cbd7b42afbd8.p12','notasecret');
if ($success != true) {
    print $cert->lastErrorText() . "\n";
    exit;
}

// 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->get_LastMethodSuccess() != true) {
    print $http->lastErrorText() . "\n";
    exit;
}
else {
    print 'access token: ' . $accessToken . "\n";
}

// 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 = new CkMailMan();

// Set the properties for the GMail SMTP server:
$mailman->put_SmtpHost('smtp.gmail.com');
$mailman->put_SmtpPort(587);
$mailman->put_StartTLS(true);

$mailman->put_SmtpUsername('bob@yourcompany.com');
$mailman->put_OAuth2AccessToken($accessToken);

// Create a new email object
$email = new CkEmail();

$email->put_Subject('This is a test');
$email->put_Body('This is a test');
$email->put_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) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

$success = $mailman->CloseSmtpConnection();
if ($success != true) {
    print 'Connection to SMTP server not closed cleanly.' . "\n";
}

print 'Successfully sent email using Gmail with a service account key.' . "\n";

?>