Roadie tries to make sending HTML emails a little less painful in Rails 3 by inlining stylesheets and rewrite relative URLs for you.

[Rails] The Exception Notifier plugin provides a mailer object and a default set oftemplates for sending email notifications when errors occur in a Railsapplication.

Rails plugin for sending asynchronous email with ActionMailer and Resque.

Send e-mail straight from forms in Rails with I18n, validations, attachments and request information.

3rd party dependency-free solution how to monitor performance of your Rails applications.

Test your ActionMailer and Mailer messages in Capybara

Rails performance tests (removed from core in Rails 4.0)

The Postmark Rails Gem is a drop-in plug-in for ActionMailer to send emails via Postmark, an email delivery service for web apps.

Rails plugin for sending asynchronous email with ActionMailer and Resque

Rails plugin for sending asynchronous email with ActionMailer and Resque

Rails observer (removed from core in Rails 4.0)

[description]

Gem to extend ActionMailer with SendGrid API support

Best practice is to send text/plain && text/html markdown works great for both, so why write your templates twices?

An adapter for using Mailgun with Rails and Action Mailer

Easy SQL based report generation with the ability to accept request parameters and render multiple formats.

Ruby wrapper for Mailjet's v3 API

This gem instruments your Ruby on Rails application using InfluxDB.

Database-backed Rails error subscriber

Mail safe provides a safety net while you're developing an application that uses ActionMailer. It keeps emails from escaping into the wild. Once you've installed and configured this gem, you can rest assure that your app won't send emails to external email addresses. Instead, emails that would normally be delivered to external addresses will be sent to an address of your choosing, and the body of the email will be appended with a note stating where the email was originally intended to go.