Formatting: Increase minimum characters allowed in is_email() to 6.

Brings the minimum characters expected for a valid email address to six, which matches the expectations in `wp_handle_comment_submission()` and REST API email arguments.

Props rmccue, lukecavanagh, rachelbaker, desrosj, sudar.
Fixes #38708.

Built from https://develop.svn.wordpress.org/trunk@40667


git-svn-id: http://core.svn.wordpress.org/trunk@40530 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/formatting.php

@@ -2872,7 +2872,7 @@ function is_email( $email, $deprecated = false ) {
 		_deprecated_argument( __FUNCTION__, '3.0.0' );
 
 	// Test for the minimum length the email can be
-	if ( strlen( $email ) < 3 ) {
+	if ( strlen( $email ) < 6 ) {
 		/**
 		 * Filters whether an email address is valid.
 		 *
@@ -3109,7 +3109,7 @@ function iso8601_to_datetime( $date_string, $timezone = 'user' ) {
  */
 function sanitize_email( $email ) {
 	// Test for the minimum length the email can be
-	if ( strlen( $email ) < 3 ) {
+	if ( strlen( $email ) < 6 ) {
 		/**
 		 * Filters a sanitized email address.
 		 *