Missing Emails: HAREDIRECT, Shadow Servers & ... ?

We have just moved offices and domain, being a small company (<10 users) I did this as a clean install of Exchange 2013 SP1 on Win Server 2012 R2- the following problem occurred from the off on the new server.

Email deliverability seems fine except that we are not receiving NDRs for failed delivery of emails from our web server. This hasn't changed and is therefore not the source of the problem. The return path is bounce@ which is a group for support@ which is group for the support user (me).

In Message Tracking I was seeing the messages with "SourceContext: No suitable shadow servers" & "EventId: HAREDIRECTFAIL" errors. Disabling of Shadow Redundancy has cleared these.

So now the messages come in with EventID of RECEIVE (the email coming in), RESOLVE (resolving the recipient) and then a third log entry of AGENTINFO:

RunspaceId              : d666cc75-c98c-42f5-bacd-f2090564b4b8
Timestamp               : 12/06/2014 10:08:38
ClientIp                :
ClientHostname          : mail
ServerIp                :
ServerHostname          :
SourceContext           :
ConnectorId             :
Source                  : AGENT
EventId                 : AGENTINFO
InternalMessageId       : 1662152343578
MessageId               : <201406120906.s5C7xUIu003247@web1.OUR-DOMAIN>
Recipients              : {bounce@OUR-DOMAIN}
RecipientStatus         : {}
TotalBytes              : 9513
RecipientCount          : 1
RelatedRecipientAddress :
Reference               :
MessageSubject          : Warning: could not send message for past 4 hours
Sender                  : MAILER-DAEMON@web1.OUR-DOMAIN
ReturnPath              : <>
Directionality          : Incoming
TenantId                :
OriginalClientIp        : OUR-WEB-SERVER-IP
MessageInfo             :
MessageLatency          :
MessageLatencyType      : None
EventData               : {[AMA, SUM|v=0|action=|error=|atch=2], [AMA, EV|engine=M|v=0|sig=1.175.2005.0|name=|file=],
                          [CompCost, |AMA=0], [DeliveryPriority, Normal]}

The emails then disappear?

I noticed the empty return-path but have disabled all antispam features that I can see through the EMC.

We run Kaspersky Security 8.0 which I have (temporarily) disabled and configured it to keep copies of emails when deleting/rejecting. There is no sign of them in there.

I realise there is CU5 available but I was holding off on that before due to history of updates introducing further problems.

Thanks for any advice.