Need help. I'm flooding my school with mail requests and need to block it on my end.

I talked to my schools security guy and he told me that my home's external IP address is showing up as sending way to many requests to their mail server. I believed it was my new galaxy note 8 because its mail setting were set to auto so I tried to limit it by setting it to manual. I also want to block the mail server on my firewall/router I have a fortigate 60c at my house. I have a policy that says all internal traffic is allowed to go to WAN1(policy 9). But above that I have a policy that says deny all traffic from internal that is going to the two mail server ip addresses at my campus (policy 8).

Am I doing something wrong? Shouldn't policy 8 block all data from going to the ip addresses? I did it by making firewall objects and put it in policy 8 as a deny all traffic.

Any and all help would be appreciated, my campus has put a global block on my home external IP until this gets figured out because apparently it is a dangerous amount of traffic and they think my equipment is compromised... it all started when I got my new phone, and I have tracked the usage in my logs to my new phone.