Title: Return Path = Critical Error
Last modified: February 17, 2021

---

# Return Path = Critical Error

 *  Resolved [pwizard](https://wordpress.org/support/users/pwizard/)
 * (@pwizard)
 * [5 years, 3 months ago](https://wordpress.org/support/topic/return-path-critical-error/)
 * If RETURN PATH contains an email, actions within the admin interface involving
   sending out emails (such as resending notification for example).give a CRITICAL
   ERROR. Also happens on live site after attempting to subscribe.
 * Nothing comes up in logs.
 * If Return PAth is empty, it is fine

Viewing 6 replies - 1 through 6 (of 6 total)

 *  Thread Starter [pwizard](https://wordpress.org/support/users/pwizard/)
 * (@pwizard)
 * [5 years, 3 months ago](https://wordpress.org/support/topic/return-path-critical-error/#post-14098208)
 * No response in a week. Doesn’t bode well for deciding to upgrade to a paid version.
 * Call to undefined function PHPMailer\PHPMailer\ctype_alnum
 * (PHP 7.4)
    -  This reply was modified 5 years, 3 months ago by [pwizard](https://wordpress.org/support/users/pwizard/).
 *  Plugin Author [Stefano Lissa](https://wordpress.org/support/users/satollo/)
 * (@satollo)
 * [5 years, 3 months ago](https://wordpress.org/support/topic/return-path-critical-error/#post-14118877)
 * Hi, return path does not produce critical error, usually, but your provider can
   have filters active specially if your return path is a non existent address or
   with a different domain than yours.
 * You can find some notes here:
 * [https://www.thenewsletterplugin.com/documentation/installation/newsletter-configuration/](https://www.thenewsletterplugin.com/documentation/installation/newsletter-configuration/)
 * Stefano.
 *  Thread Starter [pwizard](https://wordpress.org/support/users/pwizard/)
 * (@pwizard)
 * [5 years, 3 months ago](https://wordpress.org/support/topic/return-path-critical-error/#post-14119211)
 * The emails are valid.
 * This is the debug log ONLY WHEN I PUT EMAIL IN RETURN PATH
 * [01-Mar-2021 20:31:09 UTC] PHP Fatal error: Uncaught Error: Call to undefined
   function PHPMailer\PHPMailer\ctype_alnum() in /mypath/wp-includes/PHPMailer/PHPMailer.
   php:1745
    Stack trace: #0 /mypath/wp-includes/PHPMailer/PHPMailer.php(1815): 
   PHPMailer\PHPMailer\PHPMailer::isShellSafe(‘bounce@mywebsite..’) #1 /mypath/wp-
   includes/PHPMailer/PHPMailer.php(1613): PHPMailer\PHPMailer\PHPMailer->mailSend(‘
   Date: Mon, 1 Ma…’, ‘This is a multi…’) #2 /mypath/wp-includes/PHPMailer/PHPMailer.
   php(1444): PHPMailer\PHPMailer\PHPMailer->postSend() #3 /mypath/wp-includes/pluggable.
   php(498): PHPMailer\PHPMailer\PHPMailer->send() #4 /mypath/wp-content/plugins/
   newsletter/includes/mailer.php(386): wp_ in /mypath/wp-includes/PHPMailer/PHPMailer.
   php on line 1745
 *  Plugin Author [Stefano Lissa](https://wordpress.org/support/users/satollo/)
 * (@satollo)
 * [5 years, 3 months ago](https://wordpress.org/support/topic/return-path-critical-error/#post-14119306)
 * That is an error of the PHPMailer library in WP. Please ask the provider to install
   the ctype PHP extension.
 *  Thread Starter [pwizard](https://wordpress.org/support/users/pwizard/)
 * (@pwizard)
 * [5 years, 3 months ago](https://wordpress.org/support/topic/return-path-critical-error/#post-14119455)
 * It works under PHP 7.0 through 7.3. Not PHP 7.4
 *  Plugin Author [Stefano Lissa](https://wordpress.org/support/users/satollo/)
 * (@satollo)
 * [5 years, 3 months ago](https://wordpress.org/support/topic/return-path-critical-error/#post-14121047)
 * You php 7.4 installation could be missing the ctype extension.

Viewing 6 replies - 1 through 6 (of 6 total)

The topic ‘Return Path = Critical Error’ is closed to new replies.

 * ![](https://ps.w.org/newsletter/assets/icon-256x256.png?rev=1052028)
 * [Newsletter - Send awesome emails from WordPress](https://wordpress.org/plugins/newsletter/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/newsletter/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/newsletter/)
 * [Active Topics](https://wordpress.org/support/plugin/newsletter/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/newsletter/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/newsletter/reviews/)

 * 6 replies
 * 2 participants
 * Last reply from: [Stefano Lissa](https://wordpress.org/support/users/satollo/)
 * Last activity: [5 years, 3 months ago](https://wordpress.org/support/topic/return-path-critical-error/#post-14121047)
 * Status: resolved