Looking for a document that compares features and funtionality between BlackBerry and OMA. Can you limit devices the company can support and apply a policy that would prevent clients from downloading software to the device.

OMA is a lookalike of OWA .. It does not have the enhanced features of OWA. Used in 2003. The default url is https://localhost/oma., It is a sort of web based application... I hope your question is understood

Agree with Khoj. OMA is just a mailbox access method on the device To restrict download action, ActiveSync mailbox policy has an option that relates to it “Allow attachments to be downloaded to device” Resources: Security Considerations on the Exchange ServerPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.