After a small misadventure with Rsync I had to delete and remigrate a bunch of former cPanel domains.
Afer migration I was unable to connect to the server to pop email from one of the domains because it said that quotas were exceeded. (I am afraid that I haven't got the exact message.)
I noticed that in 'Webmin' - 'Edit Mail and FTP Users' the 'Quota Used' was above the 'Disk quota' number. Although the 'Quota used' for the actual email address was below the Disk quota. Currently the Quota Used is 315.27 Mb, whereas dh -ch shows 70Mb.
I discovered that if you delete the virtual server and reinstall it, the quota used goes up, even though it is the same domain as was just deleted.
Perhaps this is bandwidth quota (but I don't have it switeched on)? Is there a way to make Virtualmin recalculate filesystem quotas? I tried 'Check disk quotas', but it made no difference.