Hi Debi,
Thanks for your post. Here are the answers for your questions.
1. Is there any notification I can signup for in auth.net to notify me that my webhook is in danger of being (or has been) inactivated due to max retries?
We have developed a feature where we notify you with an email, if your webhook is in danger of being inactivated. We try sending a wehook notification 10 times before we inactivate the webhook. We will send an email after 6 retries saying there is something wrong with the webhook, and after 10 retries we send another email saying the webhook has been deactivated. This feature is not in production yet, but hopefully will be there soon.
2. Once the webhook was made active again new ones are coming through fine however it doesn't appear that the ones that would have been sent during the period of inactive status will be retried or resent. Can someone confirm? Is there a way that we can push these "lost" webhooks back through?
Events happened while the webhook subscription was inactive will not be converted to notofications. Unfortunately there is no way to push those lost webhooks notifications.
Hope this helps!