Real-time messaging

Remind https://www.remind.com/  Real time messenger that allows you to schedule posts to any device while protecting personal contact information.

Appletree https://www.goappletree.com/ I met the Appletree team at ISTE 2016 and if I wasn’t already invested in Remind, then I would seriously be considering this option.

Twitter https://twitter.com/ Less directed than the other two options, but you can increase effectiveness by using a consistent hashtag for your group whether it be colleagues, students, or families you are wanting to connect with. Can be scheduled using tools such as Hootsuite or TweetDeck.