MailChimp is a very nicely done service, where they tell you things like %clicked, and Google Analytics of recent email campaigns. They are similar to other sites like ConstantContact and CampaignMonitor, and many many others.
Is there anything similar to MailChimp which is open-source or free?
Or is there anything that could be easily modified to resemble mailchimp for use in-house?
It is simply too expensive once you have a couple thousand email addresses.
Any ideas would be helpful.
I prefer any languages, but ideally HTML/PHP/MySQL...
* double opt-in subscription mechanism * scheduling * RSS * list segmentation * click-tracking * attachments * bounce management