Gail,
Knowing your audience and how to communicate best with them is essential. I was at a confernce a couple of weeks ago and another online instructors said he asks his class how they want him to communicate with them. He gives them the option of a Facebook group, Blackboard discussion board, or email. They choose one and that's how he communicates with them. Then, they are responsible for checking the one area because it's the one they chose.
Thanks.