Kangal brings you a nice set of custom validators for Rails 4.

Daily standup automation for easier collaboration

MailCatcher REST API SDK

MailGate is an additional delivery method for the Mail gem that lets you restrict the delivery of mail to only whitelisted emails.

mailinator-spec is a library for using mailinator for testing email from rspec and cucumber

Messenger: easy message sending for various protocols.

LTI mountable engine

Pig Media Server

Rack middleware to send email when exceptions are raised

Deliver mail in a resque job

A unified interface for various messaging queues

Roust is a Ruby API client to access Request Tracker's REST interface.

Rumbster is a simple SMTP server that receives email sent from a SMTP client. Received emails are published to observers that have registered with Rumbster. There are currently two observers; FileMailObserver and MailMessageObserver.

RUby Simple Exception Notification (a.k.a. rusen) as it names indicates is a simple exception notification for ruby.

Application framework for state based session management

Sensu monit plugins

Sensu sms plugins

SMTP Proxy for Amazon Simple Email Service with bounce and complaints support

SimplePostmark makes it easy to send mails via Postmark using Rails's ActionMailer.

SimplePostmark makes it easy to send mails via Postmark™ using Rails 3's ActionMailer.