How can I find out why a subscription has failed to send out? What is the name of the log file and where can it be found?

Hi,

I have this error on a timed subscription

Failure sending mail: An error has occurred during report processing.

This report runs flawlessly and has been for months. I tried looking for the log file that contains the errors to help with troubleshooting. Can anyone help me out?

Thanks,
R