OpenEMM is a feature-rich enterprise software for professional newsletter and email marketing. It offers sophisticated bounce management, link tracking, lots of statistics and a script feature to set up transaction mails (data, event and time triggered).
OpenEMM is the first open source application for e-mail marketing. Its code base has been developed since 1999 and is used (as part of the commercial ASP product E-Marketing Manager) by companies like IBM, Siemens and Deutsche Telekom.
OpenEMM offers already more than 90% of the functionality of the commercial product does not offer right now (i.e. MySQL support).
The main difference is, that OpenEMM is an easy to set up single server solution, while its big brother E-Marketing Manager operates on several distributed servers as ASP.