Resend

Signature Verification

Property	Value
Algorithm	Svix HMAC-SHA256
Headers	svix-id, svix-timestamp, svix-signature
Timestamp tolerance	300 seconds (5 minutes)

Resend uses Svix for webhook delivery. Transyt uses the official Svix library to verify signatures, which handles the HMAC-SHA256 computation, timestamp validation, and signature comparison.

Setup

1. In the Resend Dashboard, go to Webhooks
2. Add a new webhook endpoint:

   https://ingest.transyt.com/resend/{your-account-slug}

3. Copy the Signing secret provided by Resend

Account Configuration

curl -X POST https://ingest.transyt.com/admin/accounts \
  -H "X-Admin-Token: YOUR_ADMIN_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "provider": "resend",
    "account_slug": "main",
    "app_key": "my-app",
    "signing_secret_current": "whsec_..."
  }'

Event Type Mappings

Email Events

Resend Event	Transyt Event
email.sent	email.sent
email.delivered	email.delivered
email.delivery_delayed	email.delivery_delayed
email.bounced	email.bounced
email.opened	email.opened
email.clicked	email.clicked

Contact Events

Resend Event	Transyt Event
contact.created	contact.created
contact.updated	contact.updated
contact.deleted	contact.deleted

Domain Events

Resend Event	Transyt Event
domain.created	domain.created
domain.updated	domain.updated
domain.deleted	domain.deleted

External ID

The external ID is a composite of event_type:email_id or event_type:object_id, depending on the event type.