Sendmux

Sendmux is an email inbox API for AI agents that lets developers give agents real mailboxes, controlled outbound sending, live inbox events, and developer tools in one platform. Instead of stitching together a sending API, mailbox provider, parser, webhook service, and separate billing system, teams can use Sendmux as the email API layer for agents that need to send, receive, route, and react to email in production.

Sendmux supports dedicated agent mailboxes on the included myagent.mx domain or verified custom domains. Agents can read messages, threads, folders, attachments, identities, usage, quotas, submissions, and mailbox metadata through the Mailbox API. They can also send, reply, reply-all, and forward from a mailbox, with clean extracted content available so agents can process new replies without parsing raw email manually.