Every email your app sends while you build and test it lands in OwlMail's browser inbox instead of a customer's mailbox. Point any application's SMTP settings at OwlMail and every message is ready to open as rendered HTML, plain text, headers, or raw source. Attachments and inline images sit beside the body, and seven preset preview widths show how the message lays out on phones, tablets, and desktops before anyone real sees it. A Verify panel checks subject, body, and link hosts against expectations, while CI pipelines use the REST API with delivery cursors to wait for exactly the messages their test run produced, assert on them, and clean up afterwards. Coding agents get the same inbox read-only over MCP, so an assistant can confirm a signup email arrived without touching your mail server. When a message proves itself, relay it onwards to a real SMTP server, by hand or automatically under filtering rules, or fire webhooks with HMAC signatures and retry queues into the rest of your automation. Everything stores as plain .eml files on disk, with optional SQLite indexing, S3 attachment storage, and ZIP exports for archiving. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.