A delivery counts as successful when your URL answers with an HTTP 2xx code within 10 seconds. Anything else (timeout, 4xx, 5xx, network error) is a failure.
Retries
Mailpro retries automatically with increasing delays: 10 s → 1 min → 5 min → 30 min → 2 h → 6 h → 24 h, i.e. 7 attempts over a little more than a day. Every attempt carries the X-Mailpro-Attempt header and the same X-Mailpro-Event-Id, so your processing must be idempotent.
Automatic disabling
After 10 consecutive failures the webhook switches to Disabled and no more events are sent (the reason and date are shown in the list). Once your server is fixed, click Reactivate and fix.
Events that occurred while the webhook was disabled are not replayed. If you miss the status of a send, you can always query it: delivery status via the API.
Diagnosing
View delivery history (Settings → Webhooks) lists every attempt with the HTTP code returned, the latency, the next scheduled attempt and the last error. The Replay button recreates the delivery immediately. The payload sent is not stored: correlate with your own logs using the Event ID.
Mailpro and webhooks
Beyond failed callbacks — webhooks that keep trying
Mailpro's SMTP and API deliver your transactional and marketing email with real-time events, so your app always knows what happened.