Index: wp-mail.php
===================================================================
--- wp-mail.php	(revision 11256)
+++ wp-mail.php	(working copy)
@@ -13,6 +13,14 @@
 /** Get the POP3 class with which to access the mailbox. */
 require_once( ABSPATH . WPINC . '/class-pop3.php' );
 
+/** Keep certain intervals to fetch mail messages. */
+if ( !defined('WP_MAIL_INTERVAL') )
+	define('WP_MAIL_INTERVAL', 300); // 5 minutes
+
+if ( !WP_MAIL_INTERVAL || ( WP_MAIL_INTERVAL > time() - get_transient('mailserver_last_checked') ) )
+	exit;
+set_transient('mailserver_last_checked', $last_checked);
+
 $time_difference = get_option('gmt_offset') * 3600;
 
 $phone_delim = '::';