Dada Mail : Dada Mail is a Contemporary Mailing List Manager, enabling you to easily run a verified mailing list that your subscribers can trust, right on your ow...
SimpleLogin : With email aliases , you can be anonymous online and protect your inbox against spams and phishing. Open-source.
SquirrelMail : SquirrelMail is a standards-based webmail package written in PHP. It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages...
Cachet : Beautiful & simple service statuses. The open source status page system, for everyone.
Maily Herald is a Ruby on Rails engine that helps you send and manage your mailings.
Think of Maily as a self-hosted Mailchimp® you can easily integrate with your site.