hi Leonne
I felt angry reading about the teammate who contacted you "with a blast highlighted in red" & I sense my impulse to want to teach this person some manners (silly, I know, & it's not as if this approach would do any good).
But IMO your post illustrates such a strong core reason for developing a sense of genuine community: we do it because it creates a safe, supportive environment for learning, & because engaged, connected students are more likely to stay the course. And because it's the kind thing to do.
At College of the Rockies, we had an informal "Lost Souls" policy. It went something like this: if you haven't seen your online student log in by the end of the first week, contact them (preferably by phone in case there's a problem with internet connection). And if you don't hear from them for over 2 weeks, contact them. Most instructors did this anyway but the occasional instructor would actively resist with the argument: "My students are adults & if they don't bother to participate in the class, that's their problem." My return argument was "Caring about and contacting your students is also adult behaviour" ... but this was not always effective. :-/
I like your checklist approach! It is simple, definitely not intimidating (even to a student with weak technical skills), communicates your concern while keeping the onus for contact with the student. This would be a great way to maintain contact even with students in asynchronous self-paced online programs -- notoriously hard to build community in those settings.