Question : Block BlackBerry Access in Exchange

We have over 9000 email users on Exchange 2003. The company has OWA enabled and all the mobile email is through Windows mobile smartphones using active sync. A few people are using blackberry which is against company policy and they use Blackberry Internet Services to get their email. To do that they have to provide their email credentials to a thrid party website which is again against company policy.

Since there are too many of these users it is hard to regulate them, so I wanted to block BIS from accessing OWA. Is there a way of completly shutting down black berry access in Exchange server.

Thank you

Answer : Block BlackBerry Access in Exchange

What about blocking the IP range of the blackberry devices used