Question regarding sent emails

Question regarding sent emails

Good day.

I have a problem that I can't find a solution to.

As of right now, I am the newest employee to my team. A part of my job is to create a list of those that we haven't contacted in a while. when I dig through these leads, I scroll all of the way through and I find that this person has not been contacted in any manner. My co-worker, can see all of the emails anyone has sent to this particular person. I can't see any emailed leads whatsoever before 12/10/16.

Basically I can't see any emails sent to a person past 12/10/2016(which is also the day I started in this company), and he can.

How do I fix this ?