Evernym

Notifier is the simple, private, free way to reach everyone in a group how they each prefer, and know they got your message. The group leader uses the powerful Notifier app to notify group members, who don't need the app to receive them. Members get messages how they each prefer: email, text, the "Notifier" app, or any internet connection. Group leaders can also finally stop gathering and maintaining lists of everyone's contact info, as the members can take care of that themselves, with complete privacy.