Cannot route fax through e-mail "The Fax Service failed to execute a specific routing method"

I'm struggling to get our Fax service on a Windows SBS 2011 server to route to email. Faxes receive normally into the Windows Fax and Scan inbox, but ever since implementing SBS 2011 it hasn't worked. Perhaps it's a configuration issue but I'm not sure.

In the Application logs we get error 32089;

"The Fax Service failed to execute a specific routing method. The service will retry to route the fax according to the retries configuration. If the retries fail, verify routing method configuration.
Job ID: 0x0401ce41015ec4c6.
Received on Device: 'USB Soft Data Fax Modem with SmartCP'
Sent from: 'USER'
Received file name: 'C:\ProgramData\Microsoft\Windows NT\MSFax\Queue\1CE41015EC4C6.tif'.
Routing extension name: 'Microsoft Routing Extension'
Routing method name: 'Route through e-mail'"

Any ideas?