Using Quickbooks online I get emails saying " An Error has occurred while performing an operation with AvaTax. Your are receiving this email because we are unable to connect to Intuit to validate your token, or your token is INVALID. You recieve an update in an hour if the problem persists"
This email is sent as a result of the service checking credentials with Intuit, which it does every 3 minutes or so. This email will generate if for any reason the credentials cannot be validated and is not necessarily the sign that there is an ongoing issue. You can stop these email notifications if you wish by signing in to Intuit and changing the notifications email under the preferences tab. Website address is https://www.avataxforqbo.com/