smtp4dev

smtp4dev eliminates the need for live SMTP servers during development by providing a local dummy server that captures emails safely. Compatible with Windows, Linux, and Mac, it includes OpenAPI/Swagger, IMAP/POP3 access, and SMTP logging. Test UTF8 support, viewport sizes, and multipart MIME structures, while HTML reports and validation tools ensure compatibility. It handles TLS/SSL modes, authentication, and multiple mailboxes with rule-based routing. Developers can reply, compose, relay messages, and apply scripting expressions to simulate scenarios like delivery failures, streamlining email testing workflows.