Docusign PHP SDK resending envelope with Demo Account updates the envelope but no email is sent

I am trying to resend an existing envelope that a user may have mislaid or otherwise not received. The API is updating the envelope with the request, but is not resending the email. I am receiving a 200 OK response from the api. This is my call;

$envelopeApi->update($account_id, $env_id, json_encode([resend_envelope => true]));

The logs show the call is successful;

PUT https://demo.docusign.net:7801/restapi/v2/accounts/eb84945a-xxxx-xxxx-xxxx-125dae50be01/envelopes/1e748673-xxxx-xxxx-xxxx-d932f6bdb90e
Content-Type: application/json
Content-Length: 24
Transfer-Encoding: chunked
Accept: application/json
Authorization: Bearer [omitted]
Host: demo.docusign.net
User-Agent: Swagger-Codegen/2.0.1/php
X-DocuSign-SDK: PHP
X-SecurityProtocol-Version: TLSv1.2
X-SecurityProtocol-CipherSuite: ECDHE-RSA-AES256-GCM-SHA384
x-forwarded-for: 

{"resend_envelope":true}

200 OK

Content-Type: application/json; charset=utf-8
Content-Length: 60
X-DocuSign-TraceToken: 3f4d4386-xxxx-xxxx-xxxx-ede4199f7f35

{
  "envelopeId": "1e748673-xxxx-xxxx-xxxx-d932f6bdb90e"
}

I have read all the threads I can find on SO and none seem to cover my experience. Your help would be appreciated.

Answer

For anyone stumbling across this post, this is how to resend an envelope using v2 of the PHP SDK, as provided by dev support. Its a shame the SDK isn’t better documented.

$options = new DocuSigneSignApiEnvelopesApiUpdateOptions();
$options ->setResendEnvelope("True");
$results = $envelopeApi->update(self::$accountID, $envelopeid, "{}", $options);

Thanks to Edwin@DS