Can't e-mail MS Excel from AX

I can run a report and e-mail every report format EXCEPT Excel.  I keep getting a permission error:

The permissions granted to user '(user)' are insufficient for performing this operation.

UPDATE

Such a simple answer for this...  The DAX service account, and other user accounts, must be set up as 'Browser' in the Report folder.

Add a 'New role assignment' and give your DAX service account, user accounts, or user groups access as 'Browser'.

And it works!