Communication Error [334]

Please help. I am experiencing an error in sending the Thank You emails. This is the error: “Communication Error [334] – make sure the Envelope From email is the same account used to create the Client ID.”

Here is the diagnostic:

Mailer: postsmtp
HostName: sylfoundation.org
cURL Version: 7.66.0
OpenSSL Version: OpenSSL/1.1.1n-fips
OS: Linux giowm1056.siteground.biz 3.12.18-clouder0 #2 SMP PREEMPT Mon Mar 7 20:55:37 EET 2022 x86_64
PHP: Linux 7.4.28 C
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=No, zlib_encode=Yes
WordPress: 5.9.3 en_US UTF-8
WordPress Theme: Essentials Child
WordPress Plugins: Seamless Custom by Brendan, Classic Editor, Classic Widgets, Simple Custom CSS and JS, Elfsight Facebook Feed CC, Elfsight Team Showcase CC, Envato Market, WPBakery Page Builder, Kali Forms Payments, Kali Forms Pro, Kali Forms - WordPress Forms Made Easy, pixfort Core, Post SMTP, Slider Revolution, Seamless Donations, TranslatePress - Multilingual, YellowPencil
WordPress wp_mail Owner: /home/customer/www/sylfoundation.org/public_html/wp-content/plugins/post-smtp/Postman/PostmanWpMailBinder.php
WordPress wp_mail Filter(s): TRP_Translation_Render->wp_mail_filter, wp_staticize_emoji_for_email, PostsmtpMailer->get_mail_args
WordPress phpmailer_init Action(s): PostsmtpMailer->phpmailer_smtp_init
Postman: 2.0.25
Postman Sender Domain (Envelope|Message): sylfoundation.org | sylfoundation.org
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: SMTP (smtp:tls:oauth2://smtp.gmail.com:587)
Postman Active Transport Status (Ready|Connected): Yes | Yes
Postman Deliveries (Success|Fail): 24 | 23

Thank you

The page I need help with: [log in to see the link]