Global limits, quota per user for all services.
I know that ISPConfig is multiserver and because of that limits are separated per web quota, email and database quota. As i posted question here it looks like i understood exactly how it works and answer that i got is that there is no global limit per user account.
However it would be nice to implement some kind of functionality that count together all service quota and apply limits on global rate.
So for example if i set global limit of 5GB per user, i don't need to set separate limits per web, email or database so all of that should be counted together per user global limit. So if user use 3gb of web storage for files, he have remaining 2 gb for emails and database.
Now i need to set 3GB for web storage limit, 1.5GB for email and 500MB for database, and if user want to have more space for email i need to go manually and decrease web limit to 2.5GB and increase email to 2GB.
It would be much better if we can just set 5GB limit to all services on global rate per user and user can use them however he want.
You can use a shared quota by enabling 'Use Websites Linux uid for mailbox' under System > Server config > Mail.
But I would never do that on any of my systems as it allows web scripts to access your emails (as they have to share the same Linux user (owner) to have the same quota limit), so when someone hacks your site, then he can read and delete your emails.
And that's just one of the reasons why we do not use that by default. Beside that, it won't work on multiserver systems anyway as the Linux system quota does not span over multiple servers.