Not sending

Hi I’ve been having a major problem… Notifications from my website are not sent (emails, form registrations etc.)!!! I manages to fix the probelm by installing postman-smtp, everything worked but I don’t know how long it worked because now (and for a few weeks now)… Not working!
Here’s the code:

OS: Linux a2plcpnl0254.prod.iad2.secureserver.net 2.6.32-531.29.2.lve1.3.11.10.el6.x86_64 #1 SMP Fri Jun 12 15:09:02 EDT 2015 x86_64
HTTP User Agent: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:38.0) Gecko/20100101 Firefox/38.0
Platform: PHP Linux 5.4.43 / WordPress 4.2.3 fr_FR
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=Yes
WordPress Theme: Photolab-Child
WordPress Plugins: Gravity Forms, Akismet, Connections, Custom Sidebars, Google Analytics by Yoast, Gravity Forms Logging Add-On, Gravity Forms PayPal Standard Add-On, Jetpack by WordPress.com, MailChimp for WordPress Lite, Meta Slider, Postman SMTP, UpdraftPlus – Backup/Restore, Use Any Font, Wordfence Security, Yoast SEO
Postman Version: 1.6.23
Postman Sender Domain (Envelope|Message): ecuriesnamaste.com|ecuriesnamaste.com
Postman Prevent Message Sender Override (Email|Name): No|No
Postman Transport URI: smtp:none:none://relay-hosting.secureserver.net:25
Postman Transport Status (Configured|Ready|Connected): Yes|Yes|Yes
Postman Deliveries (Success|Fail): 8|30
Postman Bind (Success|Fail|Path): Yes|No|/home/ecuriesnamaste/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

Thank you for helping me!

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