MailCatcher

Ruby SMTP catcher with web UI — the original.

Visit MailCatcher Start free with MailKite

How MailKite fits

MailCatcher is for Ruby dev. MailKite is for production send + receive.

Send email from MailCatcher with MailKite

A minimal, copy-paste starter. Swap in your own domain and API key.

send.ts

import { MailKiteClient } from "@mailkite/client";

// One API, your own DKIM-signed domain — no mail server to run
const mailkite = new MailKiteClient({ token: process.env.MK_API_KEY! });

await mailkite.send({
  from: "you@yourdomain.com",        // any address on a verified domain
  to: "user@example.com",
  subject: "Hello from MailCatcher",
  html: "<p>Sent in milliseconds via MailKite.</p>",
});

Read the sending quickstart

MailCatcher is the original Ruby SMTP catcher (gem, MIT) that inspired MailHog. It catches SMTP on :1025 and shows mail in a web UI on :1080. Maintained slowly; many new stacks use Mailpit instead.