Enfold generating errors from WP SMTP Mail plugin

I use the WP SMTP Mail plugin.

Enfold is generating regular errors from the plugin. Here’s the error report:
Debug Event Details
Type
Error
Date
July 7, 2025 at 2:06 pm
Content
Mailer: Other SMTP
SMTP Error: data not accepted.SMTP server error: DATA END command failed Detail: Spam message rejected
SMTP code: 554 Additional SMTP info: 5.7.1
Source
Enfold
/home/storage/322/4077322/user/htdocs/wp-content/themes/enfold/framework/php/class-form-generator.php (line: 1485)

I just found out the errors actually started in April 2024 but as I use the free version of the plugin I don’t get notified via email when an error occurs so I’d only notice it if I logged in to the WP admin panel and there had been a recent error (as I did today). Unfortunately when there is a successful send of an email the plugin clears the error flag from the admin bar which is why I only discovered this today.

The errors are generated at random intervals. There have been one a day for the past 3 days, prior to that it was June 30, two on June 28, two on June 26, June 25, June 24, June 22, June 3, May 31 etc.

Any ideas?

WordPress 6.8.1, Enfold 7.1.1