Deny users to create Domains

[apinto]

Yup! That's a good solution and I would use it.

But, just to keep thinking about this You can always have different user levels, for example:
- Packages will limit the amount of things (500mb space, 3 sub domains, etc).
- User Levels would limit the available modules.
With this you can have some users on the same package but with different levels.

A use case for this would be to allow your users to pay for the ability to add a main domain while keeping the free account usage limits.