diff --git a/send-smtp-email.php b/send-smtp-email.php
index e67b588019c5672b4f1af7b3be9d4b77d4ddf5b5..e5d11ba1e61d84c2c9c1322b62d4491b44217240 100644
--- a/send-smtp-email.php
+++ b/send-smtp-email.php
@@ -34,3 +34,11 @@ if (defined('SMTP_HOST')) {
 	}
 }
 
+/**
+ * Handler to log email failures.
+ */
+function log_mail_failure($wp_error) {
+    error_log('SMTP error: ' . print_r($wp_error, true));
+}
+
+add_action('wp_mail_failed', 'log_mail_failure', 10, 1);