Issues with mail traffic volumes stats

Hello,

Firstly, my server is an AWS EC2 Cloud Instance. Here's all the tech specs:

CPU Intel(R) Xeon(R) CPU E5-2676 v3 @ 2.40GHz (1 core(s))
Version Plesk v12.5.30_build1205150826.19 os_Ubuntu 14.04
OS Ubuntu 14.04.4 LTS
Key number PLSK.[correct number is here]
System Uptime: 55 day(s) 19:39

So, the issue is this: the stats for email usage data say that for a particular one of my clients, their total usage is very...

Issues with mail traffic volumes stats