Hi @treanormp
This is an indication that a character set conversion is not working on your PHP environment as exptected. There is a fallback method (using a different approach) which is likely to work in your case, otherwise you would see missing/empty subject or message contents.
So I don’t that problem has any impact.
Thank you for considering my problem. I think my system diagnostics error was a red herring. I learned from mxtoolbox that my ip address was “Added to Spamhaus ZEN” on 3/23/2025 11:32:15 PM and remained until 4/3, which of course includes the date of our group’s attempted conversation. My ip address was also on a UCEPROTECTL3 blacklist. But the last time Spamhaus was the issue my send report was clear about the emails not processing. Despite the clean report, could that be it? If you like, I will make up a small list to test this theory. Thank you again.
I did not notice until now that WordPress had sent me an error notification on March 5th, well prior to my issue but possibly related since my WP-Mailster version (1.8.21.0) has not been updated since then. I have removed the site-specific info; let me know if that makes it harder to debug:
Howdy!
WordPress has a built-in feature that detects when a plugin or theme causes a fatal error on your site, and notifies you with this automated email.
In this case, WordPress caught an error with one of your plugins, wp-mailster.
First, visit your website () and check for any visible issues. Next, visit the page where the error was caught () and check for any visible issues.
Please contact your host for assistance with investigating this issue further.
If your site appears broken and you can't access your dashboard normally, WordPress now has a special "recovery mode". This lets you safely login to your dashboard and investigate further.
https://.../wp-login.php?action=enter_recovery_mode&rm_token=dbSGmcmExZhcHIhmcJNZgs&rm_key=y0gDmWsp7q8Dz16IcFFau3
To keep your site safe, this link will expire in 1 day. Don't worry about that, though: a new link will be emailed to you if the error occurs again after it expires.
When seeking help with this issue, you may be asked for some of the following information:
WordPress version 6.7.2
Active theme: Twenty Seventeen (version 3.8)
Current plugin: (version )
PHP version 8.3.6
Error Details
=============
An error of type E_ERROR was caused in line 63 of the file .../public_html/wp-content/plugins/wp-mailster/wp-mailster.php. Error message: Uncaught Error: Failed opening required '.../public_html/wp-content/plugins/email-subscribers/.../public_html/wp-content/plugins/wp-mailster//mailster/includes.php' (include_path='.:/opt/cpanel/ea-php83/root/usr/share/pear') in /.../public_html/wp-content/plugins/wp-mailster/wp-mailster.php:63
Stack trace:
#0 /home1/.../public_html/wp-content/plugins/wp-mailster/wp-mailster.php(1581): wpmst_mailster->__construct('/home1/site...')
#1 /home1/.../public_html/wp-settings.php(526): include_once('/home1/site...')
#2 /home1/.../public_html/wp-config.php(103): require_once('/home1/site...')
#3 /home1/.../public_html/wp-load.php(50): require_once('/home1/site...')
#4 /home1/.../public_html/wp-login.php(12): require('/home1/site...')
#5 {main}
