Does ZCB support Native File Support on BES so I can use Documents To Go to view my documents on my Blackberry?

Today when I open an attachment on an e-mail on my Blackberry it only utilizes the Blackberry viewer and does not give the option to open with Documents to Go, but when I open an attachment on the same Blackberry from an e-mail from with my home ISP it asks if you want to open with Docs To Go. Not sure if this is a setting issue with the BES or ZCB.