Sendmux

Sendmux is an email API that gives every AI agent a real inbox. Send and receive, route outbound through your own providers, and fail over automatically.

Create agent inboxes, send through your providers, and route with quotas, weighted delivery, and failover from one API. You stitch together two or three services, manage separate APIs, and pay separate bills. Gmail and Outlook return full HTML email bodies that consume thousands of LLM tokens. Current platforms lock you into their sending infrastructure. One API surface for outbound mail, agent mailboxes, routing controls, and delivery events.