Delivery Failure on System Emails

When I first installed your plugin I was getting both contact form messages and system messages just fine. Now system messages come to my domain email with a delivery failure because it’s been marked as spam. These are supposed to go to my Gmail and it used to work. I just sent a test mail through your plugin and that arrived at my Gmail fine. For example today the email letting me know that I was automatically upgraded to WP 4.7.3 behaved this way. Here’s the diagnostic info as you asked. Please advise.

PHP: Linux 7.1.1 C
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=Yes, zlib_encode=Yes
WordPress: 4.7.3 en_US UTF-8
WordPress Theme: Spacious
WordPress Plugins: BackWPup, Category Sticky Post, Contact Form 7, Custom Meta Widget, Disqus Comment System, Easy Google Fonts, Exclude Pages from Navigation, Flamingo, Google Analyticator, Google Custom Search, Hello Bar (Official), IP Geo Block, Jetpack by WordPress.com, Local Search SEO Contact Page, Postman SMTP, SEO Ultimate, TinyMCE Advanced, Revive Old Post (Former Tweet Old Post), Wordfence Security, WP Author Box Lite
WordPress wp_mail Filter(s): wp_staticize_emoji_for_email
WordPress wp_mail_from Filter(s): wordfence::fixWPMailFromAddress
WordPress phpmailer_init Action(s): wpcf7_phpmailer_init
Postman: 1.7.2
Postman Sender Domain (Envelope|Message): reikihelp.com | gmail.com
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: SMTP (smtp:tls:login://mailx2.newtekwebhosting.com:25)
Postman Active Transport Status (Ready|Connected): Yes | Yes
Postman Deliveries (Success|Fail): 34 | 6