# ryanb/letter_opener

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3,841 stars · 244 forks · Ruby · MIT

## Links

- GitHub: https://github.com/ryanb/letter_opener
- awesome-repositories: https://awesome-repositories.com/repository/ryanb-letter-opener.md

## Description

Letter Opener is a development email sandbox and interceptor for Ruby on Rails. It functions as an SMTP mocking tool that captures outgoing emails and saves them to the local file system, preventing messages from being delivered to real addresses during the development cycle.

The project provides a local email previewer with a web interface. This allows for the visual verification of email layouts, content, and headers directly in a browser.

The tool manages intercepted communications through directory-based artifact management and integrates directly into the application mailing pipeline to substitute standard mail delivery.

## Tags

### Testing & Quality Assurance

- [Email Delivery Testing](https://awesome-repositories.com/f/testing-quality-assurance/email-delivery-testing.md) — Verifies the construction, content, and recipients of emails generated by application mailers without sending them to real users.
- [Email Previewers](https://awesome-repositories.com/f/testing-quality-assurance/ruby-on-rails-testing-frameworks/email-previewers.md) — Allows developers to inspect email content and headers locally within a browser. ([source](https://github.com/ryanb/letter_opener#readme))
- [SMTP Server Mocks](https://awesome-repositories.com/f/testing-quality-assurance/smtp-server-mocks.md) — Replaces the standard mail delivery class with a local interceptor to prevent emails from reaching real addresses.
- [Development Sandboxes](https://awesome-repositories.com/f/testing-quality-assurance/email-delivery-testing/development-sandboxes.md) — Provides a controlled sandbox environment for testing email delivery logic without requiring external providers.

### Development Tools & Productivity

- [Local Email Previewers](https://awesome-repositories.com/f/development-tools-productivity/local-email-previewers.md) — Provides a web interface to visually verify email layouts and styles directly in the browser.
- [Rails Development Utilities](https://awesome-repositories.com/f/development-tools-productivity/rails-development-utilities.md) — Enhances the Ruby on Rails development workflow by capturing and previewing generated emails.

### DevOps & Infrastructure

- [Local Delivery Interceptors](https://awesome-repositories.com/f/devops-infrastructure/infrastructure/networking/messaging-infrastructure-integrations/mail-delivery-agents/local-delivery-interceptors.md) — Redirects outgoing messages to the local file system instead of external SMTP servers. ([source](https://github.com/ryanb/letter_opener#readme))

### Web Development

- [Email Interceptors](https://awesome-repositories.com/f/web-development/email-interceptors.md) — Captures outgoing Ruby on Rails emails and saves them locally to prevent delivery to real addresses.
- [Ruby on Rails Integrations](https://awesome-repositories.com/f/web-development/ruby-on-rails-integrations.md) — Hooks directly into the Ruby on Rails mailing pipeline to automatically capture messages.