Loss of Exchange effects on SharePoint 2007

My company has opted (without input from the IT Section) shut down our Exchange Server and outsource our email and Blackberry services to an outside vendor. We have an MOSS 2007 Enterprize installation in place.
We are trying to compile a list of checkpoints and considerations to verify with the vendor that these items will be part of the services they provide. What checkpoints and expected degregation issues can we expect with this course of action?