I don't believe an application for Android would be the best focus in my own opinion. We have invested a significant amount of time and resources in improving the web interface and ensuring it is mobile compatible. Because of this, the webmail interface works sufficiently on most mobile devices and includes all of the expected functionality when using an email client like Outlook or Thunderbird.
With that being said; the framework you choose to deploy will depend on your requirements for your application. I can confirm that SmarterMail is an entirely .NET based application and will require a Windows based server to operate.
Kyle Kerst
IT Coordinator
SmarterTools Inc.
www.smartertools.com