JotNot Scanner's fax functionality is accessible from JotNot's main screen.  Tap the fax machine icon in the lower left to open the Faxing page.  Tap on "Sent Faxes" to see a list of the faxes that you've sent with JotNot.  Each row in this list has an icon that reports the status of each fax -- a green checkmark for a successful fax, a spinning circle for a pending fax, and a red circle with an X in it for a failed fax.  You can tap on any row to get more details about the fax.

You may also want to consider using JotNot's fax notifications to get status information about your faxes, so you don't have to actively monitor your fax status -- if this sounds interesting to you, please check out our article about turning on fax notifications:

We report faxes as successful when we receive a confirmation from the receiving fax equipment that tells us that it received the fax in full. Please note that we cannot identify when the wrong person picks up the fax from the fax machine, or if the fax printer jams, or if a variety of other (pretty uncommon) things prevent the right person from receiving your fax. The only way to tell for sure that the right person got it is to ask them directly.

Thank you for using JotNot, the best scanner app for iOS!