Outlook REST API Webhooks Subscription Retry if Application has Crashed

Question

I would like to use the Outlook REST API webhooks / subscriptions to update calendar events in my application. I couldn't find any information in the documentation regarding whether the Outlook API will retry sending Notifications if my application is down / crashed or sends a 500 error. I know the Google API uses exponential backoff to retry sending. Does Outlook do something similar?

Thanks, Adam

Answer 1

Yes. From the Microsoft Graph documentation:

When the subscribed resource changes, the webhooks facility sends a notification to your notification URL with the following payload. The notification endpoint must send a response of 200 or 204 with no response body within 30 seconds otherwise the notification attempt will be retried at exponentially increasing intervals. Services that consistently take 30 seconds or more may be throttled and receive a sparser notification set.