Cannot Send Test Email

Here is my diagnostic information. My email provider is google. What other steps can I take to determine why my user registration emails are not sending?

OS: Linux http://www.poteckpower.com 3.19.0-20-generic #20-Ubuntu SMP Fri May 29 10:10:47 UTC 2015 x86_64
PHP: Linux 5.6.4-4ubuntu6.4 en_US.UTF-8
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=No, zlib_encode=Yes
WordPress: 4.2.5 en_US UTF-8
WordPress Theme: Avada
WordPress Plugins: LayerSlider WP, Adminer, Contact Form DB, Contact Form 7, Custom Upload Dir, Dropbox Backup & Restore, Favicon XT-Manager, Fusion Core, Google Analytics, Insert PHP, JM Twitter Cards, Page Restrict, PDF Embedder Premium, Postman SMTP, Pure Chat, Revolution Slider, Simple Custom CSS, TablePress Extension: PHP in tables, TablePress, Theme My Login, Twitter, UpdraftPlus – Backup/Restore, User Meta Manager, WordPress File Upload Pro, WP Hide Dashboard, Media Library Categories, Google Forms, Google XML Sitemap Generator
WordPress wp_mail Filter(s): wp_staticize_emoji_for_email
WordPress wp_mail_from Filter(s): Theme_My_Login_Custom_Email->mail_from_filter
WordPress wp_mail_from_name Filter(s): Theme_My_Login_Custom_Email->mail_from_name_filter
WordPress wp_mail_content_type Filter(s): Theme_My_Login_Custom_Email->mail_content_type_filter
Postman: 1.7.2
Postman Sender Domain (Envelope|Message): gmail.com | poteckpower.com
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: SMTP (smtp:none:none://smtp.gmail.com:587)
Postman Active Transport Status (Ready|Connected): Yes | Yes
Postman Deliveries (Success|Fail): 0 | 0

https://wordpress.org/plugins/postman-smtp/