HELO

HELO runs a local SMTP server that intercepts outgoing messages from a developer’s application, allowing the content to be inspected without actually delivering the mail. It presents each message with its HTML rendering, plain‑text version, source code and full header list, and supports unlimited per‑project inboxes so that multiple applications can be tested in parallel.

The tool includes automated checks such as a broken‑link validator that confirms every URL returns an HTTP 200 response, and an optional SpamAssassin score lookup to flag messages that might be marked as spam. Users can forward intercepted emails to teammates, share entire inboxes, or create public remote mailboxes that receive messages from external sources and display them inside the desktop app.

HELO also offers a view inspector that can be integrated via an open‑source helper package for frameworks like Laravel, enabling developers to debug mail templates directly. The combination of local capture, content review, link verification, spam scoring, and sharing features targets web developers who need a straightforward, on‑machine solution for testing and debugging email output.