Not saying this is your issue but its some thing you can look over.
once you look over it please post any magt mast logs that you have after.
Mixed windows domain.
View Document
LDAP setup
View Document
No records were found that match the specified search criteria
View Document
Send As revoked beacuse install on DC and no local admin
The xxx34;Send Asxxx34; right is removed from a user object after you configure the xxx34;Send Asxxx34; right in the Active Directory Users and Computers snap-in in Exchange Server
BlackBerry Messaging Agent log shows "Failed to read 001e6602 reg value from the BlackBerry MAPI profile"
Also messaging agent failed to start error code 5305
BlackBerry Technical Solution Center