Problems with sending e-mail via Postman using Contact Form 7

I’m unsure to post this issue here or on Contact Form 7 support. I’ll start here ??

The Issue
I’ve just installed and setup Postman to send e-mails when visitors use the contact form (Contact Form 7) on my website. When testing Postman with ‘Send a Test Email’ It successfully send a e-mail which I successfully receive. (https://postimg.org/image/k1rnqc1fb/).

When I do a diagnostics test I get the following results.

OS: Linux Groenendaal-NAS 3.2.40 #5592 SMP Wed Aug 19 13:37:13 CST 2015 armv7l
HTTP User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.80 Safari/537.36
PHP: Linux 5.5.28 en_US.UTF-8
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=Yes
WordPress: 4.3.1 en_US
WordPress Theme: ColorMag
WordPress Plugins: bbPress, BuddyPress, Contact Form 7, Postman SMTP, YouTube
WordPress wp_mail Filter(s): wp_staticize_emoji_for_email
WordPress wp_mail_from_name Filter(s): bp_core_email_from_name_filter
Postman: 1.6.24
Postman Sender Domain (Envelope|Message): gmail.com | gmail.com
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Transport URI: smtp:tls:oauth2://smtp.gmail.com:587
Postman Transport Status (Configured|Ready|Connected): Yes | Yes | Yes
Postman Deliveries (Success|Fail): 0 | 4

The connectivity test has the following results
https://postimg.org/image/lya01lw43/

When I press the send button using the webform I recieve the message as seen bellow.
Failed to send your message. Please try later or contact the administrator by another method.

I’m not an extremely technical guy ?? but google usually is your best friend. This time I’m unsure where the problem is. Could you please help me? If you need additional info please let me know.

Thank you so much in advance!!

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