Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 10782)
+++ wp-includes/formatting.php	(working copy)
@@ -1516,7 +1516,8 @@
 
 	// LOCAL PART
 	// Test for invalid characters
-	if ( !preg_match( '/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]+$/', $local ) ) {
+	$local = preg_replace( '/[^a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]/', '', $local );
+	if ( '' === $local ) {
 		return apply_filters( 'sanitize_email', '', $email, 'local_invalid_chars' );
 	}