É chamado de "Acesso a Arquivos de Computador" ou "Acesso Direto a Arquivos", mas acho que isso só está disponível através do OWA, e não por outros meios (ou seja, diretamente do Smartphone do cliente de e-mail interno)
Direct file access lets users open files that are attached to e-mail messages and files that are stored in Windows file shares. You can manage direct file access for Microsoft Office Outlook Web App in Microsoft Exchange Server 2010 for both public and private computers.
By default, public computer direct file access is enabled for new installations and upgrades of Outlook Web App. Therefore, when users in your organization select This is a public or shared computer or This is a private computer on the Outlook Web App sign-in page, they will be able to access files that are attached to e-mail messages.
Para detalhes, veja aqui: link