Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 39166)
+++ wp-includes/formatting.php	(working copy)
@@ -2865,7 +2865,7 @@
 		_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.
 		 *