We're having a problem receiving emails promptly at my organization. There can be anywhere from a short delay or emails arrive almost 24 hours after being sent. On thing I've noticed is that in email headers I am getting the HELO at the same time of the original send time. Then there is a delay before the next Received: entry which is when the email enters the network. For example: Received: from www.xxx.com ([192.168.0.zzz]) by 02.xxx.com with Microsoft SMTPSVC(6.0.3790.3959); Tue, 19 Jun 2007 00:45:24 -0400 Received: from yyy.co.uk ([212.100.zzz.zzz]) by www.xxx.com with Microsoft SMTPSVC(6.0.3790.1830); Tue, 19 Jun 2007 00:45:23 -0400 Received: from localhost ([127.0.0.1] helo=list.xxx.co.uk) by xxx.co.uk with esmtp (Exim 4.50) id 1I0U9n-0008D2-0R for qqq@xxx.com; Tue, 19 Jun 2007 04:13:27 +0100 See how the helo was received at 03:13:27 UTC but the email then didn't arrive at the network until 4:45:23 UTC? This is actually a fairly quick delivery though, this newsletter is often delayed 12+ hours between the helo and the email receipt.