Using emails is highly effective with the online learners. There are protocols that should be followed to ensure that the emails are used effectively and should have set guidelines to follow. 

continuous assessment of your own teaching style will help prepare you to successfully teach the various and diverse learning styles of students. 

creating an online authority and presence is a skill that needs to be practiced while still making yourself, as an instructor, approachable and have students understand that you available to help.

It takes multiple layers of both on the technical side and the instructor side to effectively prepare students for success.