Has someone seen this issue?

I have a mixed environment with Exchange 2010 and 2013. I am currently working on getting Exchange 2013 up and running in the environment. Exchange 2010 is fully functional. Here is the issue I am having. 

Here is how the emails are flowing. I have a primary site and a DR site. 

1) Emails from my SMTP Gateway hit the Exchange 2010 CAS Server (Receive Connector)
2) Email goes to Exchange 2013 CAS Server located at the DR Site (SMTP Relay to Remote AD Site)
3) RecipientStatus         : {452 4.3.1 Insufficient system resources}
ConnectorId             : Intra-Organization SMTP Send Connector
ClientHostname          : Exchange 2010 CAS
ServerIp                : IP
ServerHostname          : Exchange 2013 CAS
SourceContext           :
ConnectorId             : Intra-Organization SMTP Send Connector
Source                  : SMTP
EventId                 : DEFER
InternalMessageId       : 10
MessageId               :
Recipients              :
RecipientStatus         : {452 4.3.1 Insufficient system resources}
TotalBytes              : 3844
RecipientCount          : 1

4) Exchange 2010 (Retry)
5) Email goes to Exchange 2013 CAS Server located at the DR Site (SMTP Relay to Remote AD Site)
6) RecipientStatus         : {452 4.3.1 Insufficient system resources}
ConnectorId             : Intra-Organization SMTP Send Connector
7) Exchange 2010 (Retry)
8) Email sends through Exchange 2010 CAS Server

ServerHostname          : Exchange 2010 CAS Server
SourceContext           :
ConnectorId             : Intra-Organization SMTP Send Connector
Source                  : SMTP
EventId                 : SEND
InternalMessageId       10
MessageId               :
Recipients              :
RecipientStatus         : {250 2.1.5 Recipient OK}

I have engaged Microsoft and there are no indications of Back Pressure and no events in the Event Viewer indication errors. The CAS Server currently has 8 GB of memory which is enough because the CAS server is currently doing nothing because I'm still using Exchange 2010 in the environment. This only happens during (SMTP Relay to Remote AD Site).

How are you on space?

It might be helpful to take a look at these two blog posts..

http://blogs.msdn.com/b/echarran/archive/2007/04/30/4-3-1-insufficient-system-resources-in-exchange-server-2007.aspx

http://exchangepedia.com/2007/03/exchange-server-2007-transport-452-4-3-1-insufficient-system-resources.html

Hi,

In addition to the above suggestion, please make sure that the network service account have proper permission to the Exchange folder. If no, please give permission to network service account and check the result.

Hope this can be helpful to you.

Best regards,