How to send an email with attachments using the Mail gem?

Use the `add_file` method in a Mail block or assign attachments directly, e.g., `mail.attachments['file.pdf'] = File.read('path.pdf')`. Mail automatically encodes attachments in Base64 and guesses MIME types, handling the details for you.

Mail gem vs Action Mailer in Rails: what's the difference?

Action Mailer is built on top of Mail and is integrated into Rails for convenience with helpers and templates. Use Mail directly for non-Rails projects or when you need lower-level control over email parsing and generation without Rails dependencies.

Does Mail support UTF-8 in email subjects and bodies?

Yes, Mail supports RFC6532 for UTF-8 headers and bodies, leveraging Ruby's modern text encoding support. It handles international characters properly in both parsing and generation of emails.

How to test emails sent with Mail in RSpec?

Set the delivery method to :test using `Mail.defaults { delivery_method :test }`, then inspect `Mail::TestMailer.deliveries`. Mail provides RSpec matchers for assertions on email properties like subject, body, and attachments.

Can Mail retrieve emails from Gmail using IMAP?

Yes, configure the retriever_method with IMAP settings: use `Mail.defaults { retriever_method :imap, address: 'imap.gmail.com', port: 993, enable_ssl: true }`. Then, methods like `Mail.all` or `Mail.first` fetch emails for processing.

How to parse a .eml file with Mail?

Use `Mail.read('/path/to/file.eml')` to load and parse the email. You can then access headers, body, attachments, and multipart sections through the Mail object's methods, such as `mail.subject` or `mail.attachments`.

Open-Awesome

Mail

MITRuby2.9.1

A Ruby library for email generation, parsing, and sending with a simple, idiomatic API.

GitHub

3.7k stars940 forks0 contributors

What is Mail?

Mail is a Ruby library that provides a complete solution for handling email generation, parsing, and sending. It simplifies working with email by offering an intuitive API for creating multipart messages, managing attachments, and interacting with SMTP, POP3, and IMAP servers. The library is designed to be robust and RFC-compliant while maintaining a Ruby-like elegance.

Target Audience

Ruby developers who need to integrate email functionality into their applications, whether for sending transactional emails, parsing incoming messages, or testing email-related features.

Value Proposition

Developers choose Mail for its comprehensive feature set, idiomatic Ruby API, and strong focus on reliability and testing. It replaces older libraries like TMail with modern encoding support and a cleaner design, making email handling straightforward and error-resistant.

Overview

A Really Ruby Mail Library

Use Cases

Best For

Adding email sending capabilities to Ruby web applications
Parsing and processing incoming email in Ruby scripts
Creating multipart emails with HTML and text alternatives
Testing email functionality in Rails or other Ruby frameworks
Handling email attachments with automatic encoding
Integrating with POP3 or IMAP servers to retrieve emails

Not Ideal For

Projects requiring direct integration with cloud email APIs like SendGrid or Amazon SES without SMTP fallback
Real-time, high-volume email processing systems needing streaming or async capabilities
Non-Ruby environments or polyglot teams where language-agnostic solutions are preferred

Pros & Cons

Pros

RFC Compliance and Robustness

Supports RFC5322 and RFC6532 for parsing US-ASCII and UTF-8 emails, with a design that never crashes on unexpected input—it skips problems and continues parsing, ensuring data integrity.

Flexible Delivery and Retrieval

Offers multiple delivery methods (SMTP, sendmail, Exim, file logging) and email retrieval via POP3/IMAP, providing a unified interface for all email operations in Ruby.

Built-in Testing Utilities

Includes TestMailer for unit testing and RSpec matchers for email assertions, making it easy to test email functionality without sending actual emails in development.

Automatic Attachment Handling

Encodes attachments in Base64, guesses MIME types, and provides simple methods for adding and extracting attachments, reducing boilerplate code for file handling.

Cons

Incomplete MIME Support

The README admits that MIME support for character sets in headers needs refinement, which can lead to issues with complex or non-standard email formats.

Ruby-Only Limitation

As a pure Ruby library, it's not suitable for projects in other languages, forcing teams to seek alternatives if they operate in polyglot environments.

Configuration Overhead

Setting up advanced delivery methods like Exim or custom SMTP configurations requires manual intervention and can be more complex compared to simpler email libraries.

Frequently Asked Questions

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