diff --git a/src/wp-includes/pluggable.php b/src/wp-includes/pluggable.php
index c53a723fc4..b5e39d7a19 100644
--- a/src/wp-includes/pluggable.php
+++ b/src/wp-includes/pluggable.php
@@ -158,6 +158,8 @@ if ( ! function_exists( 'wp_mail' ) ) :
 	 * be set using the {@see 'wp_mail_charset'} filter.
 	 *
 	 * @since 1.2.1
+	 * @since 5.5.0 is_email() is used for email validation,
+	 *              instead of PHPMailer's default validator.
 	 *
 	 * @global PHPMailer\PHPMailer\PHPMailer $phpmailer
 	 *