I like to start my school year with 7th graders by having them review their school gmail accounts. Students tend to be very unorganized with their email account so we spend some time creating labels or just deleting emails from when they were in 4th grade.
I use gmail to notify students of grades or missing work or when tests are coming up. I also use it to communicate with parents. Since we were unable to have true parent-teacher conferences I utilized gmail to email student progress reports for parents who wanted an update on their child's performance in class.
I like the feature on google classroom that emails students of any new post, assignment deadline, or a grade received.