From: Mail Administrator <Postmaster@example.com>
Subject: [Warning] Email server usage is approaching quota

Please be aware that you are approaching your email storage quota
on the mail server.  Future mail deliveries may be refused if you 
exceed your quota.

Please move any messages you no longer need on the server to your 
local email folders.  You may also want to check any "Sent Messages", 
"Trash" or "Deleted Items" folders for email that no longer needs to 
be on the server.

Thank you for your quick attention to this matter!

Sincerely,
Mail Administrator