There are several internal MS Exchange 2007 and MS Exchange 2010 servers running Symantec Mail Security for Microsoft Exchange 6.5 (or above).  These Exchange servers do not have access to the Internet and so cannot successfully download the latest antivirus definitions via LiveUpdate. 

To keep them up-to-date, an internal LiveUpdate Administrator 2.x (LUA 2.x) server is installed on a network server that can access the Internet.  It is set up per the instructions in the following excellent articles:

Installation and configuration of LUA
https://www-secure.symantec.com/connect/articles/installation-and-configuration-lua

Configuring Distribution Center in LUA
https://www-secure.symantec.com/connect/articles/configuring-distribution-center-lua

Additional instructions can be found in the following official Symantec article, though it is specific to SMSMSE 6.0.9.  Most of the recommendations and steps for SMSMSE 6.5 are identical, but for clarity this Connect Forum article will show precisely what selections are needed for 64-bit SMSMSE 6.5.5 servers.

Distributing virus definitions for Symantec Mail Security for Microsoft Exchange (SMSMSE) via LiveUpdate Administrator 2.x.
Article: TECH96018 
Article URL http://www.symantec.com/docs/TECH96018

___________________________________________________________________________________________

Once logged in to LUA 2.x, with the "Symantec Mail Security for Microsoft Exchange 6.5" product added to the Distribution Center, click on Download & Distribute, "Add Download Schedule."

Give this new scheduled task a name like "SMSMSE 64-bit."

It only really needs to be configured to run once per day, as certified SMSMSE definitions are released one time per day.

Click "Add" to chose the product components that will be downloaded.....

On that "Select products to be added" page, place a check mark beside everything EXCEPT "SMSMSE Virus Definitions 5.0" as those are 32-bit only definitions.  (All Exchange 2007 and Exchange 2010 servers are 64-bit, so no 32-bit SMSMSE definitions will be needed in this example.)

Do not be confused by the naming structure.  Though the definitions have the description "SMSMSE Virus Definitions wow64 5.0 " these are indeed the correct antivirus definitions for SMSMSE version 6.5.

Once those have been added, review the Download job's details and click OK.

Next be sure to Add Distribution Schedule (otherwise the downloaded SMSMSE definitions will never be used!) 

Give the task a name, add the Symantec Mail Security for Microsoft Exchange 6.5 English product, and set it to distribute definitions to the Production Distribution Centers that is used by the SMSMSE servers.

For LiveUpdate Administrator 2.3 and above, it is recommended to select the option to distribute After Download Schedule, and select the SMSMSE scheduled download job.  This means that as soon as the definitions have been successfully retrieved from the Internet LiveUpdate source servers by LUA 2.x, they will be automatically distributed and made available to the SMSMSE servers on the network.  

Click OK.

Be sure to monitor the LUA 2.x Event Log for any errors that may occur with downloading or distributing the files! 

Also monitor the SMSMSE servers to ensure that they are able to successfully run LiveUpdate and retrieve the certified definitions from the Distribution Center you have configured.

____________________________________________________________________________________________________________

Many thanks for reading!  Please do comment, below, if there are any points of confusion or steps which require further clarification!