diff --git a/public_html/lists/admin/class.phplistmailer.php b/public_html/lists/admin/class.phplistmailer.php
index 2887f121a..24e1b2008 100644
--- a/public_html/lists/admin/class.phplistmailer.php
+++ b/public_html/lists/admin/class.phplistmailer.php
@@ -76,7 +76,7 @@ public function __construct($messageid, $email, $inBlast = true, $exceptions = f
         if (isset($_GET['page']) && $_GET['page'] == 'send') {
             $this->inBlast = false;
         }
-        $this->Helo = getConfig('domain');
+        $this->Helo = defined('PHPMAILER_HELO') && PHPMAILER_HELO ? PHPMAILER_HELO : getConfig('domain');
 
         if ($GLOBALS['emailsenderplugin']) {
             $this->Mailer = 'plugin';
diff --git a/public_html/lists/config/config_extended.php b/public_html/lists/config/config_extended.php
index f453ac888..8734953ea 100644
--- a/public_html/lists/config/config_extended.php
+++ b/public_html/lists/config/config_extended.php
@@ -640,6 +640,10 @@
 // it can either be "ssl" or "tls" or false to not use SSL/TLS at all
 // define("PHPMAILER_SECURE",'ssl');
 
+// Hostname to use in the SMTP HELO/EHLO greeting. Defaults to the "domain" setting.
+// Set this when your SMTP server rejects the list domain as HELO (e.g. use the web server's FQDN)
+// define('PHPMAILER_HELO', 'www.mydomain.com');
+
 //# SMTP debugging
 // Enable debugging output by phpmailer when sending test emails
 // See https://phpmailer.github.io/PHPMailer/classes/PHPMailer-PHPMailer-PHPMailer.html#property_SMTPDebug