Inbound

For developers whose software has to receive and answer email, and not only send it, Inbound provides an email API and a command-line tool. Once a domain's DNS records are verified, every address on that domain can receive mail, and each message is posted to the customer's application as a JSON payload via webhook. The payload carries the sender, the subject and a thread identifier, so the receiving code can act on a message without parsing raw email.

Routing is set address by address. A support address can be pointed at one endpoint, a billing address at another, and a catch-all can take everything else. Changes can be made in the dashboard or through the API, so a new mailbox does not need a new server or a separate mail account.

Replies that stay in the same thread

Replies are sent through the same API, and the service sets the In-Reply-To and References headers so that an answer lands inside the customer's existing conversation. Support desks benefit, and so do AI agents that must sustain a multi-message email exchange. Transactional sending is available through the same interface, so one integration can cover mail going out as well as mail coming in.

Tools for developers and agents

A command-line tool called inboundctl lets an agent run its own mailbox, and a TypeScript SDK is offered for developers who would rather use a library than raw requests. Plans are set by the monthly volume of email and the number of domains, with unlimited mailboxes on each domain at every level. The maker introduced the service in a Show HN post on 30 September 2026. Buyers sending customer mail through it should confirm the terms and data handling before connecting a live domain.