AJAX error on 365 Connect

Postman Logs
Mailer: phpmailer
HostName: DOMAIN21.wpengine.com
cURL Version: 7.58.0
OpenSSL Version: OpenSSL/1.1.1
OS: Linux pod-140406:apache2_74:193 5.3.0-1029-gcp #31~18.04.1-Ubuntu SMP Mon Jun 22 15:24:52 UTC 2020 x86_64
PHP: Linux 7.4.14 C
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=No, zlib_encode=Yes
WordPress: 5.5.3 en_US UTF-8
WordPress Theme: TheGem
WordPress Plugins: LayerSlider WP, Affiliate Program For WooCommerce, The SEO Framework, Classic Editor, Contact Form 7, Cookie Notice, Directorist – Business Directory Plugin, Yoast Duplicate Post, ECWD Views, Event Calendar WD Premium, Featured Images in RSS for Mailchimp & Other Email, Flamingo, Social Media Flying Icons | Floating Social Media Icon, Form Maker, reCaptcha Pro by BestWebSoft, WPBakery Page Builder, Mega Addons For WPBakery Page Builder, Modern Events Calendar Lite, Name Directory, Google Fonts Typography, Popup Builder activator, Popup Builder, Popup Builder Advanced Closing, Popup Builder Advanced Targeting, Office 365 for Post SMTP Extension, Post SMTP, Redirection, Slider Revolution, Easy Updates Manager, TheGem Theme Elements, Compress JPEG & PNG images, TotalContest – Pro, Ultimate Member, Advanced Order Export For WooCommerce, WooCommerce Zoho, WooCommerce Stripe Gateway, WooCommerce, WP Leads Builder For Any CRM Pro, WP Mail SMTP, WP-Optimize – Clean, Compress, Cache, WordPress Page Widgets, YITH WooCommerce Affiliates, YITH WooCommerce Wishlist, Zoho Campaigns, reCaptcha by BestWebSoft
WordPress wp_mail Owner: /nas/content/live/ DOMAIN 21/wp-includes/pluggable.php
WordPress wp_mail Filter(s): wp_staticize_emoji_for_email, PostsmtpMailer->get_mail_args
WordPress wp_mail_from Filter(s): WPMailSMTP\Processor->filter_mail_from_email
WordPress wp_mail_from_name Filter(s): ATBDP_Email->atbdp_wp_mail_from_name, WPMailSMTP\Processor->filter_mail_from_name
WordPress phpmailer_init Action(s): wpcf7_phpmailer_init, WPMailSMTP\Processor->phpmailer_init, PostsmtpMailer->phpmailer_smtp_init
Postman: 2.0.20
Postman Sender Domain (Envelope|Message): DOMAIN.com | DOMAIN.com
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: SMTP (smtp:tls:none://smtp.office365.com:587)
Postman Active Transport Status (Ready|Connected): Yes | Yes
Postman Deliveries (Success|Fail): 0
Thread Starter colorkarma

(@colorkarma)

1 week, 2 days ago

From: Colorkarma <[email protected]>
To: [email protected]
Date: 2021-02-15 12:03:27
Subject: Postman SMTP Test (DOMAIN21.wpengine.com)
Delivery-URI: smtp:tls:://smtp.office365.com:587

Content-Type: text/plain; charset = “UTF-8”
Content-Transfer-Encoding: 8bit

Hello!

Sent by Postman 2.0.20 – https://www.ads-software.com/plugins/post-smtp/

Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable