Article ID: 114544, created on Aug 9, 2012, last review on Apr 25, 2014

  • Applies to:
  • Operations Automation


Many BlackBerry accounts have status Not available in POA Provider or Customer Control Panel. Also BlackBerry users may experience intermittent mail delivery issues on their smartphones.


The possible reason is problems with network connectivity between BlackBerry Enterprise Server and Microsoft Exchange CAS server(s) caused by Exchange servers maintenance. BlackBerry tries to keeps MAPI session to Exchange CAS server(s) open most of the time.

If maintenance job was performed on Exchange CAS server and it was rebooted or it is offline then BlackBerry Enterprise Server will not be able to connect to CAS servers and BlackBerry accounts will be marked as Not available in POA as a result (POA queries status of accounts from BlackBerry).

If Exchange CAS servers are behind load balancer it is important to keep all servers in array online, because otherwise BlackBerry may try to establish connection with member of load balancing cluster which is offline.


Follow the advices in the BlackBerry KB article to solve the problem:

If the problem is caused by one of CAS servers in the CAS array being offline then consider to bypass NLB cluster by pointing BlackBerry directly to the specific CAS server in array which is online and works well:

  • Log into the BlackBerry Enterprise Server host
  • Open the c:\Windows\System32\drivers\etc\hosts file in text editor (e.g. Notepad).
  • Make an entry with the IP address of one of the Client Access Server nodes and the network name of the hardware load balancer. The name of the hardware load balancer will match the Exchange 2010 CAS array name.

E.g. let be IP address of the specific CAS server in array, is FQDN of the Exchange CAS array, then add the following entry to the etc\hosts file on BES server:

  • Save the file.
  • Stop the BlackBerry Controller and BlackBerry Dispatcher Services.
  • Open the cmd utility and run ipconfig /flushdns
  • Start the BlackBerry Controller and BlackBerry Dispatcher Services.

Note: to also allow for NetBIOS name resolution change the entry in the etc\hosts file to this one:    FQDN_of_CAS_Array    NetBIOS_name_of_CAS_Array
After the problem with problem CAS server is solved revert the changes back.

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