Currently you can create webhooks from Flashy dashboard only, Go to Settings > Webhooks.
Webhook Action: contact_unsubscribed
{"event": "contact_unsubscribed","body": {"feed_id": 1,"email": "sam@domain.com","contact_id": "32_hash_key","campaign_id": 1, // Only when he unsubscribe from a campgin"reason": "hard_bounce", // Only if the email is not valid}}
The response time must be below 5 seconds otherwise the Webhook fails and we will try again at least three more times.