Better POST_BY_EMAIL logic. Props Denis-de-Bernardy. fixes #11752

git-svn-id: https://develop.svn.wordpress.org/trunk@12623 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/ms-functions.php

@@ -2401,7 +2401,7 @@ function filter_SSL( $url) {
 }
 
 function maybe_cancel_post_by_email() {
-	if ( false == defined( 'POST_BY_EMAIL' ) ) {
+	if ( !defined( 'POST_BY_EMAIL' ) || !POST_BY_EMAIL ) {
 		die( __( 'This action has been disabled by the administrator' ) );
 	}
 }