Mails.ai

Mails.ai gives an AI agent its own email address through one API call, so it can send, receive and reply. Replies, deliveries and bounces reach your code as signed webhooks or a live stream, and every incoming message is scored for prompt injection before your agent reads it.

It works through SDKs for Node.js and Python, a REST API or an MCP server, so coding agents like Claude Code and Cursor can use it directly. A test key runs the whole API without sending real mail, and the free plan covers 3,000 emails a month.