Exchange Online assigns large mailbox quotas to users. These quotas are needed to cope with the volume and size of modern email. What used to take 2 KB in 1996 now consumes 60 times more. And while email is more graphical and prettier to look at, you’d wonder if the value of the actual content has changed much, if at all.
Some Exchange Online mailboxes are quite small (2 GB for frontline users). Tenant administrators might want to monitor mailbox usage to make sure that quotas aren’t unexpectedly exhausted. This post explains how to use a PowerShell script to calculate the percentage of mailbox quota used and highlight the problem if a threshold is passed.