As I find myself and my classes moving ever closer to being paperless, I also find myself with lots of emails containing assignments and shared docs. I started to delete emails from students once I graded assignments. Then I thought, maybe I shouldn't do that, maybe I might need them for some reason. So what to do with all the emails after I read them?
In my email, I created a label called 2014 STUDENT ASSIGNMENTS. I put a number at the beginning of my label so that it appears at the top of my labels and is easy to find. As I read the students assignments, I drag them to the 2014 Student Assignments label. Out of sight out of mind. If I need them in the future they are in the label. At the end of the year, I will simply delete the entire label along with--I am sure hundreds of emails from students.
Also, since I send so many emails to students, I include myself in the email as a BCC. That way, I can easy pull up any emails I emailed to students. More organization--you can filter those emails into labels.
Hope this post helps you get a little more organized with all the "e communication" you receive.