API Gmail: 400 mauvaise requête lors de l'envoi d'un e-mail (code PHP)

Je m'attendais à ce que le code ci-dessous envoie un email, mais je ne reçois que ceci:

une erreur s'est produite: erreur appelant POST https://www.googleapis.com/gmail/v1/users/me/messages/send: (400) mauvais Demande

je 200 OK utilisation de la Console des développeurs Google ici au fond. Toute aide?

$client_id = '599901532082-js1r50n20q6n5mir9fo1g81qkj9kfn3j.apps.googleusercontent.com';
$service_account_name = '599901532082-js1r50n20q6n5mir9fo1g81qkj9kfn3j@developer.gserviceaccount.com';
$key_file_location = '/tmp/APIProject-cb6558ba6435.p12';

$client = new Google_Client();
$client->setApplicationName("Client_Library_Examples");
$service = new Google_Service_Gmail($client);  

if (isset($_SESSION['service_token'])) {
  $client->setAccessToken($_SESSION['service_token']);
}
$key = file_get_contents($key_file_location);
$cred = new Google_Auth_AssertionCredentials(
  $service_account_name,
  array('https://www.googleapis.com/auth/gmail.send', 'https://www.googleapis.com/auth/gmail.compose'),
  $key
);
$client->setAssertionCredentials($cred);

if ($client->getAuth()->isAccessTokenExpired()) {
  $client->getAuth()->refreshTokenWithAssertion($cred);
}
//check if you want the validity of this string at: http://www.komeil.com/toolbox/base64decoder
//it is web safe base64 encoded email
$mime = "RnJvbTogSm9obiBEb2UgPHRpcmVuZ2FyZmlvQGdtYWlsLmVzPiANClRvOiBNYXJ5IFNtaXRoIDx0aXJlbmdhcmZpb0BnbWFpbC5jb20-IA0KU3ViamVjdDogU2F5aW5nIEhlbGxvIA0KRGF0ZTogRnJpLCAyMSBOb3YgMTk5NyAwOTo1NTowNiAtMDYwMCANCk1lc3NhZ2UtSUQ6IDwxMjM0QGxvY2FsLm1hY2hpbmUuZXhhbXBsZT4NCg0KVGhpcyBpcyBhIG1lc3NhZ2UganVzdCB0byBzYXkgaGVsbG8uIFNvLCAiSGVsbG8iLg==";


$service = new Google_Service_Gmail($client);

$msg = new Google_Service_Gmail_Message();
$msg->setRaw($mime);

try {
  $results = $service->users_messages->send("me", $msg);
  print 'Message with ID: ' . $message->getId() . ' sent.';
  return $message;
} catch (Exception $e) {
  print 'An error occurred: ' . $e->getMessage();

}

EDIT:

c'est l'objet de la requête. Il inclut les données de réponse aussi:

object(Google_Http_Request)[508]
  private 'batchHeaders' => 
    array (size=3)
      'Content-Type' => string 'application/http' (length=16)
      'Content-Transfer-Encoding' => string 'binary' (length=6)
      'MIME-Version' => string '1.0' (length=3)
  protected 'queryParams' => 
    array (size=0)
      empty
  protected 'requestMethod' => string 'POST' (length=4)
  protected 'requestHeaders' => 
    array (size=3)
      'content-type' => string 'application/json; charset=UTF-8' (length=31)
      'authorization' => string 'Bearer ya29.8gEUMiBLfxS8OLdSmpiQ-EcumeATo2qFAfPtPqwTw9fQ2zVrfZaA1X5OLoBmQccrXr8V8g' (length=82)
      'accept-encoding' => string 'gzip' (length=4)
  protected 'baseComponent' => string 'https://www.googleapis.com' (length=26)
  protected 'path' => string '/gmail/v1/users/me/messages/send' (length=32)
  protected 'postBody' => string '{"raw":"RnJvbTogSm9obiBEb2UgPHRpcmVuZ2FyZmlvQGdtYWlsLmVzPg0KVG86IE1hcnkgU21pdGggPHRpcmVuZ2FyZmlvQGdtYWlsLmNvbT4NClN1YmplY3Q6IFNheWluZyBIZWxsbw0KDQpUaGlzIGlzIGEgbWVzc2FnZSBqdXN0IHRvIHNheSBoZWxsby4gU28sICdIZWxsbycu"}' (length=214)
  protected 'userAgent' => string 'Client_Library_Examples google-api-php-client/1.0.6-beta (gzip)' (length=63)
  protected 'canGzip' => boolean true
  protected 'responseHttpCode' => null
  protected 'responseHeaders' => null
  protected 'responseBody' => null
  protected 'expectedClass' => string 'Google_Service_Gmail_Message' (length=28)
  public 'accessKey' => null

object(Google_Http_Request)[508]
  private 'batchHeaders' => 
    array (size=3)
      'Content-Type' => string 'application/http' (length=16)
      'Content-Transfer-Encoding' => string 'binary' (length=6)
      'MIME-Version' => string '1.0' (length=3)
  protected 'queryParams' => 
    array (size=0)
      empty
  protected 'requestMethod' => string 'POST' (length=4)
  protected 'requestHeaders' => 
    array (size=4)
      'content-type' => string 'application/json; charset=UTF-8' (length=31)
      'authorization' => string 'Bearer ya29.8gEUM***fxS8OLdSmpiQ-EcumeATo2qFAfPtPqwTw9fQ2zVrfZaA1X5OLoBmQccrXr8V8g' (length=82)
      'accept-encoding' => string 'gzip' (length=4)
      'content-length' => int 214
  protected 'baseComponent' => string 'https://www.googleapis.com' (length=26)
  protected 'path' => string '/gmail/v1/users/me/messages/send' (length=32)
  protected 'postBody' => string '{"raw":"RnJvbTogSm9obiBEb2UgPHRpcmVuZ2FyZmlvQGdtYWlsLmVzPg0KVG86IE1hcnkgU21pdGggPHRpcmVuZ2FyZmlvQGdtYWlsLmNvbT4NClN1YmplY3Q6IFNheWluZyBIZWxsbw0KDQpUaGlzIGlzIGEgbWVzc2FnZSBqdXN0IHRvIHNheSBoZWxsby4gU28sICdIZWxsbycu"}' (length=214)
  protected 'userAgent' => string 'Client_Library_Examples google-api-php-client/1.0.6-beta (gzip)' (length=63)
  protected 'canGzip' => boolean true
  protected 'responseHttpCode' => int 400
  protected 'responseHeaders' => 
    array (size=13)
      'vary' => string 'Origin
X-Origin' (length=15)
      'content-type' => string 'application/json; charset=UTF-8' (length=31)
      'content-encoding' => string 'gzip' (length=4)
      'date' => string 'Fri, 18 Sep 2015 08:34:25 GMT' (length=29)
      'expires' => string 'Fri, 18 Sep 2015 08:34:25 GMT' (length=29)
      'cache-control' => string 'private, max-age=0' (length=18)
      'x-content-type-options' => string 'nosniff' (length=7)
      'x-frame-options' => string 'SAMEORIGIN' (length=10)
      'x-xss-protection' => string '1; mode=block' (length=13)
      'server' => string 'GSE' (length=3)
      'alternate-protocol' => string '443:quic,p=1' (length=12)
      'alt-svc' => string 'quic=":443"; p="1"; ma=604800' (length=29)
      'transfer-encoding' => string 'chunked' (length=7)
  protected 'responseBody' => string '{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "failedPrecondition",
    "message": "Bad Request"
   }
  ],
  "code": 400,
  "message": "Bad Request"
 }
}
' (length=179)
  protected 'expectedClass' => string 'Google_Service_Gmail_Message' (length=28)
  public 'accessKey' => null