Install mailcatcher with Homebrew, Nix

Project links

• Homepage
• Repository
• Upstream docs
• Package manager page

Commands and aliases

• catchmail
• mailcatcher

Project history

The GitHub repository was created in October 2010, and the README copyright line credits Samuel Cochran from 2010 onward. MailCatcher emerged in the Ruby/Rails era where developers often needed to test application mail without sending real messages to users.

The tool's feature set stayed intentionally narrow and packageable: capture all mail, show HTML/plain/source views, rewrite embedded assets for display, expose attachments, support a sendmail-like `catchmail` helper, and provide command-line flags for SMTP and HTTP bind addresses and ports. Later releases added Docker usage examples and a simple REST-style message API.

Adoption history

MailCatcher became a well-known local mail-testing package across Ruby and web-development workflows. Official instructions cover Rails, PHP, Django, Docker, RVM, Bundler caveats, and direct RubyGems installation, showing adoption across more than Ruby-only projects.

Repository metadata shows thousands of GitHub stars and hundreds of forks. The input package-manager facts confirm Homebrew and Nix packaging, while the README recommends keeping MailCatcher out of application Gemfiles to avoid dependency conflicts, reinforcing its role as a separate developer tool.

How it is used

The standard usage pattern is to run MailCatcher as a daemon or foreground process, configure the application under test to deliver mail to `smtp://127.0.0.1:1025`, and review the results at `http://127.0.0.1:1080/`. `catchmail` lets PHP and other sendmail-oriented software hand messages to the same capture service.

Package users care about its defaults: port 1025 for SMTP, port 1080 for HTTP, and command-line options rather than a project-specific config file. That makes it easy to install globally with a package manager and use across many local projects.

Why package nerds care

MailCatcher is historically important because it made fake SMTP a one-command local service before containerized dev stacks were the default. It is small, memorable, and easy to script, which is exactly why it kept showing up in package managers.

Its packaging story also highlights a common Ruby tool issue: the README explicitly warns against putting MailCatcher in an app Gemfile because its dependencies can conflict with the application. Installing it as a system or user tool via RubyGems, Homebrew, Nix, or Docker keeps that boundary clean.

Timeline

• 2010: Public GitHub repository created.
• 2016: Older v0.6.x GitHub releases published.
• 2021: v0.8.0 release published.
• 2022: v0.8.2 release published.
• 2023: v0.9.0 release published.
• 2024: v0.10.0 release published.

Related projects

• MailCatcher is related to other local SMTP testing tools such as MailHog and Mailpit.
• It also fits alongside framework-specific mail preview tools, but differs by acting as an external SMTP server that any application can target.

Sources

• https://api.github.com/repos/sj26/mailcatcher
• https://api.github.com/repos/sj26/mailcatcher/releases
• https://github.com/sj26/mailcatcher
• https://mailcatcher.me/
• source_facts.package-manager
• source_facts.repo