A lot of online teaching is really about communicating clearly and well (even if it feels like you are stating the obvious) and establishing and managing expectations. The good news is that you can do most of that by email. Early online teaching was focussed on good organization and structure, because there simply weren’t a lot of tech options to distract us.
At its most basic, online teaching is about 3 things:
Student – content: How will you get content to students in the easiest and most accessible way? How will students engage with that content?
Instructor-student interaction: How will you as an instructor feasibly communicate with your students? And how will they communicate with you?
Student-student interaction: How will students communicate with each other and work together?