MailChip is a great service to help with long-mailing lists as well as designing email campaigns for different groups. You can design beautiful templates and them interactive. Social services such as Facebook or Twitter are integrated into MailChimp. Users can manage their subscriptions and enjoy spam-free life, selecting only those mailing lists that matter most to them.
MailChimp makes it easy to design exceptional email campaigns, share them on social networks, integrate with web services you already use, manage subscribers and track your results. It's easy to mix and match MailChimp's templates, features and integrations to suit the users need to think of it as a personal newsletter publishing platform. The system it includes a lot of features: Account Keys MailChimp, provides a keychain for account logins, Full Featured API, AutoConnect Templates, Campaign Archives.
MailChimp also has a Social Stats that makes it easy to integrate a campaigns with social networks, and find out who's liking and tweeting the users' emails. Subscriber Preferences allows subscribers to update contact information, while template Language Use makes custom templates that are easily editable. Time Warp Choose what time of day the user want the campaign delivered, and MailChimp automatically delivers at the same local time worldwide. Translation MailChimp automatically translate content, so there aren't any language barriers between the users and the international subscribers.
CSS user preferable