OpenEMM – http://www.openemm.org/

OpenEMM is a feature-rich enterprise software for e-mail marketing, newsletters and service mails (transaction mails and event or time triggered mails). OpenEMM offers sophisticated bounce management, link tracking, lots of realtime statistics, a CMS module and a scripting feature to implement individual tasks.

PHPlist – http://www.phplist.com/

phplist is a one-way email announcement delivery system.It is great for newsletters, publicity lists, notifications, and many other uses.

PHPMailer – http://phpmailer.worxware.com/

PHPMailer-ML is a Mailing List Manager and eMessage Manager. Originally created to showcase the use of PHPMailer when sending one email or when using MySQL data for your subscriber information. PHPMailer-ML uses some of our own tips and tools to maximize PHP execution time and can handle mailing lists of any size.