From b63ee5748aa1230ad6555778ad01477ac52a62eb Mon Sep 17 00:00:00 2001
From: nacin <nacin@1a063a9b-81f0-0310-95a4-ce76da25c4cd>
Date: Mon, 3 May 2010 18:54:37 +0000
Subject: [PATCH] Deprecate checkdnsrr from is_email. Unused in core, and wonky
 on some server setups (Mac OS X < PHP 5.3 specifically). A plugin can always
 add it back. props technosailor, fixes #12503.

git-svn-id: http://svn.automattic.com/wordpress/trunk@14381 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/formatting.php | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index be6ed2801d..3f1246e79e 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -1465,10 +1465,13 @@ function convert_smilies($text) {
  * @since 0.71
  *
  * @param string $email Email address to verify.
- * @param boolean $check_dns Whether to check the DNS for the domain using checkdnsrr().
+ * @param boolean $deprecated. Deprecated.
  * @return string|bool Either false or the valid email address.
  */
-function is_email( $email, $check_dns = false ) {
+function is_email( $email, $deprecated = false ) {
+	if ( ! empty( $deprecated ) )
+		_deprecated_argument( __FUNCTION__, '3.0' );
+
 	// Test for the minimum length the email can be
 	if ( strlen( $email ) < 3 ) {
 		return apply_filters( 'is_email', false, $email, 'email_too_short' );
@@ -1520,12 +1523,6 @@ function is_email( $email, $check_dns = false ) {
 		}
 	}
 
-	// DNS
-	// Check the domain has a valid MX and A resource record
-	if ( $check_dns && function_exists( 'checkdnsrr' ) && !( checkdnsrr( $domain . '.', 'MX' ) || checkdnsrr( $domain . '.', 'A' ) ) ) {
-		return apply_filters( 'is_email', false, $email, 'dns_no_rr' );
-	}
-
 	// Congratulations your email made it!
 	return apply_filters( 'is_email', $email, $email, null );
 }