I have a 2010 exchange environment and we recently started having problems with receiving external email, rebooted all mail servers, then external email went back to working for a couple of hours and now its back to not receiving external.
This is part of what i get
Remote Server returned '< #4.4.7 smtp;400 4.4.7 Message delayed>'
Original message headers:
Received: from Barracuda.Bridge.local (10.100.100.10) by DNX-Edge.bridge.local
(10.100.100.11) with Microsoft SMTP Server id 18.104.22.168; Thu, 6 Feb 2014
Received: from na01-by2-obe.outbound.protection.outlook.com
(mail-by2lp0235.outbound.protection.outlook.com [22.214.171.124]) by
Barracuda.Bridge.local with ESMTP id NO5Oso30x7uvSDcP for
<firstname.lastname@example.org>; Thu, 06 Feb 2014 10:54:51 -0700 (MST)