Gmail ideas

I am no longer teaching and work as a special education consultant.  I currently use my Gmail as part of my To Do list, using the feature of sorting all the unread emails to the top of my inbox.  If I open an email and don't have time to address it at that moment, I'll mark it as unread and come back to it later.  To do this, go to Settings, Inbox sections, and select the first section as being Unread and the section section as being Everything Else.