Sendmux

Sendmux is an email inbox API for AI agents. We built it because agents are starting to handle real workflows, but email is still mostly built around human inboxes or send-only APIs. Sendmux gives an agent a real mailbox it can send and receive from, read threads, handle attachments, reply, and react to new messages through webhooks or Server-Sent Events. For outbound email, teams can use Gmail OAuth, Outlook OAuth, SMTP providers, or managed Amazon SES, with per-provider quotas, weighted routing, health checks, and failover. The public developer surface includes REST/OpenAPI, SMTP/IMAP where needed, webhooks, SSE, MCP, SDKs, the sendmux CLI, and Sendmux Skills for agent workflows. Would love feedback from anyone building AI agents, automations, or email-heavy workflows.