Index: wp-includes/class-phpmailer.php
===================================================================
--- wp-includes/class-phpmailer.php	(revision 11070)
+++ wp-includes/class-phpmailer.php	(working copy)
@@ -1413,15 +1413,24 @@
 
     switch (strtolower($position)) {
       case 'phrase':
-        $encoded = preg_replace("/([^A-Za-z0-9!*+\/ -])/e", "'='.sprintf('%02X', ord('\\1'))", $encoded);
+        $encoded = preg_replace_callback("/([^A-Za-z0-9!*+\/ -])/",
+                                         create_function('$match',
+                                         'return "=".sprintf("%02X", ord($match[1]));'),
+                                         $encoded);
         break;
       case 'comment':
-        $encoded = preg_replace("/([\(\)\"])/e", "'='.sprintf('%02X', ord('\\1'))", $encoded);
+        $encoded = preg_replace_callback("/([\(\)\"])/",
+                                         create_function('$match',
+                                         'return "=".sprintf("%02X", ord($match[1]));'),
+                                         $encoded);
+        break;
       case 'text':
       default:
         /* Replace every high ascii, control =, ? and _ characters */
-        $encoded = preg_replace('/([\000-\011\013\014\016-\037\075\077\137\177-\377])/e',
-              "'='.sprintf('%02X', ord('\\1'))", $encoded);
+        $encoded = preg_replace_callback('/([\000-\011\013\014\016-\037\075\077\137\177-\377])/',
+                                         create_function('$match',
+                                         'return "=".sprintf("%02X", ord($match[1]));'),
+                                         $encoded);
         break;
     }
 
Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 11070)
+++ wp-includes/formatting.php	(working copy)
@@ -788,9 +788,11 @@
 	// Fixes for browsers' javascript bugs
 	global $is_macIE, $is_winIE;
 
-	/** @todo use preg_replace_callback() instead */
 	if ( $is_winIE || $is_macIE )
-		$text =  preg_replace("/\%u([0-9A-F]{4,4})/e",  "'&#'.base_convert('\\1',16,10).';'", $text);
+		$text =  preg_replace_callback("/\%u([0-9A-F]{4,4})/",
+						create_function('$hex',
+						'return "&#".base_convert($hex[1],16,10).";";'),
+						$text);
 
 	return $text;
 }