Custom webhook integration: send Inboxlee events to any tool
For teams using a sending tool without native Inboxlee support. Configure outbound webhooks for mailbox lifecycle events.
Rejwan Nirob·Jan 12, 2026·5 min readInboxlee supports outbound webhooks for the mailbox lifecycle. When a mailbox provisions, goes live, finishes warmup, or hits a deliverability alert, Inboxlee can POST a JSON payload to a URL of your choosing.
Available events
- mailbox.provisioned - DNS records applied, mailbox created
- mailbox.live - DKIM verified, mailbox marked production-ready
- mailbox.warmup_complete - 14-day warmup finished, ready for full volume
- mailbox.health_alert - placement test failed, blacklist hit, or reputation drop
- domain.expiring - 30 days before domain renewal
Configuring
In Inboxlee → Settings → Webhooks → Create. Provide a URL, select events, choose a signing secret. Inboxlee signs every payload with HMAC-SHA256 - verify the signature on your side.
Common patterns
Send mailbox.live to a Slack channel for ops visibility. Send mailbox.warmup_complete to your sending tool to lift the daily cap from the 5/day warmup floor to the 10-20/day post-warmup safe cap. Send domain.expiring to a billing system. Send mailbox.health_alert to PagerDuty for on-call escalation.
Webhook configuration takes 60 seconds. Once configured, Inboxlee handles delivery with retry-on-failure and exponential backoff up to 24 hours.
Frequently asked
What webhook events does Inboxlee fire?
Five mailbox-lifecycle events: mailbox.provisioned (DNS applied, mailbox created), mailbox.live (DKIM verified, production-ready), mailbox.warmup_complete (14-day warmup finished), mailbox.health_alert (placement drop, blacklist hit, or reputation flag), and domain.expiring (30 days before renewal). Every payload is signed with HMAC-SHA256.
How do I verify Inboxlee webhook signatures?
Configure a signing secret when you create the webhook. Inboxlee signs every payload with HMAC-SHA256 using that secret. On your endpoint, compute the same HMAC over the raw request body and compare to the signature header. Reject any request with a mismatch - that protects against forged payloads.
What happens if my webhook endpoint is down?
Inboxlee retries with exponential backoff up to 24 hours - typical schedule is immediate, 1 min, 5 min, 15 min, 1 hour, 6 hours, 24 hours. If the endpoint never recovers, the event is logged in the dashboard so you can replay it manually once you fix the receiver. No event is lost silently.
What are the most useful Inboxlee webhook patterns?
Four common ones: mailbox.live to a Slack channel for ops visibility, mailbox.warmup_complete to your sending tool to lift the daily cap from the warmup floor (5/day) to the post-warmup safe cap (10-20/day), domain.expiring to your billing system for renewal review, and mailbox.health_alert to PagerDuty for on-call escalation. Configure once, runs forever.