Setup your rails project with everything you need quickly. Not really a Gem, but everything you need is in the gem's files'.

Inventory server store and index data sent from the agent

Internet Objects for Web Applications - A unique and capable framework for quickly building web applications with Ruby

Verify that an IP is in a range

A Rails mail delivery method using Iron MQ & Workers

Write mail template components and send mail.

When mail is sent from your application, Jabber Delivery will send it to jabber uid instead of email.

Implements the JangoMail Transactional API as a custom mailer class.

Import incoming mail to your Jekyll site.

Picks the latest post and sends it by email

Generate Rails workflow engine from mind map: Freemind

Create a report easily.

Runs a JsTestDriver server + browsers with some built-in monitoring

When mail is sent from your application, kafka_mailer will put the message contents in a kafka queue.

A Rubyesque interface to Gmail, with all the tools you'll need. Search, read and send multipart emails; archive, mark as read/unread, delete emails; and manage labels. Fork of the original ruby-gmail gem (https://github.com/dcparker/ruby-gmail). Added search by subject, limit number of email...

A Gem for simple creation of backup scripts

Rubygem backend for Kensei, the Emacs mail major mode

Log all events generated by Kill Bill.

Which supports a lot of undocumented stuff.

The Kynetx Email Endpoint is a ruby gem that makes setting up an email endpoint very simple.