Send Mail with attachment using Gmail new API, but it is not displayed for receiver's inbox

Question

We are integrating GMail using the latest API provided by them as a part of developing email client within our application. We are using PHP client library provided by Google.

See the link https://developers.google.com/api-client-library/php/

In this I'm trying to send a mail with attachment. Here we have generated message/rfc822 compatible text and passed it with 'raw' parameter. Here the problem I found is, after executing the code, when I checked the sent mail for the mail which I sent via GMail API, the attachments are shown correctly. But it is not received/ displayed for the sender's mail box.

See the code for more info:

require_once DOCUMENT_ROOT . '/../library/google/src/Google/Client.php';
require_once DOCUMENT_ROOT . '/../library/google/src/Google/Service/Gmail.php';

function encodeRecipients($recipient){
    $recipientsCharset = 'utf-8';
    if (preg_match("/(.*)<(.*)>/", $recipient, $regs)) {
        $recipient = '=?' . $recipientsCharset . '?B?'.base64_encode($regs[1]).'?= <'.$regs[2].'>';
    }
    return $recipient;
}

$isAccessCodeExpired = 0;
$arrAccessToken = array();
$session = new Zend_Session_Namespace();

$client = new Google_Client();
$client->setClientId($this->client_id);
$client->setClientSecret($this->client_secret);
$client->setRedirectUri($this->redirect_uri);
$client->setAccessType('offline');
$client->setApprovalPrompt('force');

$client->addScope("https://mail.google.com/");
$client->addScope("https://www.googleapis.com/auth/gmail.compose");
$client->addScope("https://www.googleapis.com/auth/gmail.modify");
$client->addScope("https://www.googleapis.com/auth/gmail.readonly");


if ($this->getRequest()->getParam('code')) {
    $code = $this->getRequest()->getParam('code');
    $client->authenticate($code);
    $session->gmail_access_token = $client->getAccessToken();
    //$redirect = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
    $redirect = BASE_PATH . '/oauth2callback';
    header('Location: ' . filter_var($redirect, FILTER_SANITIZE_URL));
}

$isAccessCodeExpired = $client->isAccessTokenExpired();
if (isset($session->gmail_access_token) && $session->gmail_access_token != "" && $isAccessCodeExpired !== 1) {

    $client->setAccessToken($session->gmail_access_token);            
    $objGMail = new Google_Service_Gmail($client);

    $strMailContent = 'This is a test mail which is sent via using Gmail API client library.<br/><br/><br/>Thanks,<br/>GMail API Team.';
    $strMailTextVersion = strip_tags($strMailContent, '');

    $strRawMessage = "";
    $boundary = uniqid(rand(), true);
    $subjectCharset = $charset = 'utf-8';
    $strToMailName = 'To User Name';
    $strToMail = 'toemail@gmail.com';
    $strSesFromName = 'From User Name';
    $strSesFromEmail = 'fromemail@gmail.com';
    $strSubject = 'Test mail using GMail API - with attachment - ' . date('M d, Y h:i:s A');

    $strRawMessage .= 'To: ' . encodeRecipients($strToMailName . " <" . $strToMail . ">") . "\r\n";
    $strRawMessage .= 'From: '. encodeRecipients($strSesFromName . " <" . $strSesFromEmail . ">") . "\r\n";

    $strRawMessage .= 'Subject: =?' . $subjectCharset . '?B?' . base64_encode($strSubject) . "?=\r\n";
    $strRawMessage .= 'MIME-Version: 1.0' . "\r\n";
    $strRawMessage .= 'Content-type: Multipart/Alternative; boundary="' . $boundary . '"' . "\r\n";

    $filePath = '/home/server/Downloads/credentials.csv';
    $finfo = finfo_open(FILEINFO_MIME_TYPE); // return mime type ala mimetype extension
    $mimeType = finfo_file($finfo, $filePath);
    $fileName = 'credentials.csv';
    $fileData = base64_encode(file_get_contents($filePath));

    $strRawMessage .= "\r\n--{$boundary}\r\n";
    $strRawMessage .= 'Content-Type: '. $mimeType .'; name="'. $fileName .'";' . "\r\n";            
    $strRawMessage .= 'Content-ID: <' . $strSesFromEmail . '>' . "\r\n";            
    $strRawMessage .= 'Content-Description: ' . $fileName . ';' . "\r\n";
    $strRawMessage .= 'Content-Disposition: attachment; filename="' . $fileName . '"; size=' . filesize($filePath). ';' . "\r\n";
    $strRawMessage .= 'Content-Transfer-Encoding: base64' . "\r\n\r\n";
    $strRawMessage .= chunk_split(base64_encode(file_get_contents($filePath)), 76, "\n") . "\r\n";
    $strRawMessage .= '--' . $boundary . "\r\n";

    $strRawMessage .= "\r\n--{$boundary}\r\n";
    $strRawMessage .= 'Content-Type: text/plain; charset=' . $charset . "\r\n";
    $strRawMessage .= 'Content-Transfer-Encoding: 7bit' . "\r\n\r\n";
    $strRawMessage .= $strMailTextVersion . "\r\n";

    $strRawMessage .= "--{$boundary}\r\n";
    $strRawMessage .= 'Content-Type: text/html; charset=' . $charset . "\r\n";
    $strRawMessage .= 'Content-Transfer-Encoding: quoted-printable' . "\r\n\r\n";
    $strRawMessage .= $strMailContent . "\r\n";

    //Send Mails
    //Prepare the message in message/rfc822
    try {
        // The message needs to be encoded in Base64URL
        $mime = rtrim(strtr(base64_encode($strRawMessage), '+/', '-_'), '=');
        $msg = new Google_Service_Gmail_Message();
        $msg->setRaw($mime);
        $objSentMsg = $objGMail->users_messages->send("me", $msg);

        print('Message sent object');
        print($objSentMsg);

    } catch (Exception $e) {
        print($e->getMessage());
        unset($_SESSION['access_token']);
    }
}

Please help me... Thanks in advance.

Answer 1

Replace your:

$strRawMessage .= 'Content-type: Multipart/Alternative; boundary="' . $boundary . '"' . "\r\n";

with:

$strRawMessage .= 'Content-type: Multipart/Mixed; boundary="' . $boundary . '"' . "\r\n";