The issue has been resolved, but I am trying to understand exactly what went wrong. Here is the configuration.
2x Exchange 2013 Standard servers with all roles installed and setup in DAG.
1x BES server running BES Express 5.0
Windows Server 2012 R2 environment and AD level.
The BESAdmin mailbox was migrated from DB1 to DB2 which caused the following error on BES and no agents would start.
"Failed to retrieve the server DN" appears in the MAGT log with "Error 5305" and BlackBerry Messaging Agent will not start.
The fix was in this KB article. http://btsc.webapps.blackberry.com/btsc/viewdocument.do?noCount=true&externalId=KB24421
Basically the HomeMTA had no information, and I was not able to recreate the MAPI profile until the HomeMTA attribute was populated.
After some research I found that someone said Microsoft directly told them that the HomeMTA attribute is no longer used with Exchange 2013 and it will need to be filled in manually. The person that installed BES does not remember entering this information. I don't know if it was there prior to migrating the BESAdmin account to a different DB, but it definitely wasn't there when we were trying to resolve the issue. Is it possible that this attribute disappeared during a mailbox migration?
According to this article. http://btsc.webapps.blackberry.com/btsc/viewdocument.do?externalId=KB33413
Verify the HomeMTA attribute for the BlackBerry Service Account is populated: Note: This step is not required in 5.0.4 MR8 and above.
I know they are on 5.0.4, but I doubt they are on MR8. (Also not sure MR8 is available for the Express version...)
Another issue I noticed with the Exchange setup, is that Outlook AnyWhere is not configured properly with a "mail.domain.com" address. It is instead pointing to the FQDN of each server which it shouldn't be when using DAG. Not sure how this affects BES other than BES probably won't work if the Exchange server it is pointing to goes down.
Has anyone come across this issue before? Does this mean I MUST
update the HomeMTA attribute if I wish to migrate the BESAdmin mailbox in the future?