Error on sending TEST EMAIL

We are receiving the following error when trying to send out the test email:

Error calling POST https://www.googleapis.com/gmail/v1/users/me/messages/send: (403) Access Not Configured. The API (Gmail API) is not enabled for your project. Please use the Google Developers Console to update your configuration.

Our diagnostic details are as follows:

OS: Linux host354.hostmonster.com 3.12.35.1418868052 #1 SMP Wed Dec 17 20:04:02 CST 2014 x86_64
HTTP User Agent: Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.85 Safari/537.36
Platform: PHP Linux 5.4.43 / WordPress 4.3.1 en_US
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=Yes
WordPress Theme: Responsive
WordPress Plugins: Black Studio TinyMCE Widget, Connections, Contact Form 7, Debug, Events Made Easy, MOJO Marketplace, Postman SMTP, Really Simple CAPTCHA, Responsive Scrolling Tables, Simple Membership After Login Redirection, Simple Membership Custom Messages, Simple Membership WP user Import, Simple WordPress Membership, Simple Membership Form Builder, Simple Membership Google recaptcha, User Role Editor
Postman Version: 1.6.23
Postman Sender Domain (Envelope|Message): gmail.com|gmail.com
Postman Prevent Message Sender Override (Email|Name): No|No
Postman Transport URI: gmail_api:https:oauth2://www.googleapis.com:443
Postman Transport Status (Configured|Ready|Connected): Yes|Yes|Yes
Postman Deliveries (Success|Fail): 0|6
Postman Bind (Success|Fail|Path): Yes|No|/home6/gcelfuno/public_html/wp-content/plugins/postman-smtp/Postman/PostmanWpMailBinder.php
Postman TCP Timeout (Connection|Read): 10|60
Postman Email Log (Enabled|Limit|Transcript Size): Yes|10|128
Postman Run Mode: production
Postman PHP LogLevel: 40000
Postman Stealth Mode: No
Postman File Locking (Enabled|Temp Dir): Yes|/tmp

The last debug record is as follows:

[17-Sep-2015 11:18:05 UTC] ERROR PostmanWpMail: Exception code=403 message=Error calling POST https://www.googleapis.com/gmail/v1/users/me/messages/send: (403) Access Not Configured. The API (Gmail API) is not enabled for your project. Please use the Google Developers Console to update your configuration.
[17-Sep-2015 11:18:06 UTC] ERROR PostmanSendTestEmailAjaxController: Test Email NOT delivered to server – 403

Is there something else we need to setup in google developer? All previous steps prior to sending the test email worked fine.

Thank you for the assistance with this plugin.

https://ww.wp.xz.cn/plugins/postman-smtp/