Are you using Google Forms? They are amazing for many reasons. One being to have students submit their homework through so you do not have to carry papers home to grade. Grading from a spreadsheet is quite lovely.
But what about forms that you use where you get infrequent responses such as a comment form? You want to receive an email when the form has been filled out.
In the spreadsheet side of the form you want to go to the Tools Menu and choose notification rules.
From there you can choose to receive an email notification when a user submits a form.
Note, this does not notify all of the collaborators, each collaborator will need to go in and set their notifications individually.