This yes I think so, because DA does not realtime calculate how many space and bandwith is already used by resellers and all its users on packages creation. But most likely (easy to test) if you would give a reseller 50 MB and he would give a user unlimited disk access, and the user would put 100 MB, then after the tally it should be that neither reseller or user would be able to upload again.
However I'm also wondering as to how DA fixed this.
As for the mailing lists, that's odd, if the package says 0 lists, reseller should not be able to do that, unless 0 means unlimited, which would seem odd to me.
Well... I think you (or I) are confusing over what I classify as "allocation" based resellers and "usage" based resellers.
Allocation based resellers are governed by how much they allocate - how much total disk space and bandwidth they are allowed to give out to their accounts. If a reseller has 10GB of disk space to allocate out to their resold accounts, they could create 10 accounts each with a 1GB disk space quota, or 20 accounts each with 500MB of disk space, or some other configuration that adds up to 10GB of disk space. Once they've allocated their full 10GB of disk space, they can't create any new accounts.
This is in fact what happens in DirectAdmin if you try to create an account whose plan results in the reseller going over their allocation, DirectAdmin won't allow it to be created.
This negates "unlimited" in this context. If a reseller has 10GB of disk space, but they create a package with unlimited disk space - the creation happens, and how does "unlimited" add up against the 10GB reseller disk space allocation limit?
Usage based resellers are governed by how many resources their resold accounts consume collectively. This is what overselling is to me. This is tough to govern, which is why allocation based resellers are generally easier.
With a usage based reselling, a reseller with a 10GB reseller disk space allocation limit will be able to create packages and accounts with any amount of disk space. The governing system is how much disk space their resold accounts have collectively consumed. An accounts with a 10GB disk space package that is using 100MB only counts as 100MB of the reseller's 10GB disk allocation.
In this way - a usage based reseller can have access to to unlimited disk space in their package creation because it's not defined by how much disk space is allocated out, but by how much disk space is actually used.
Like I said, usage based reseller accounts are hard to govern. I'm not really asking DirectAdmin to provide a way to govern these. Most (all?) of our resellers are allocation based. For usage based resellers, I just check reseller's usage every day and determine how close they are to their resource limits.
(I used disk space in this example, but bandwidth could have been used as well)
At least this is how I've always defined these aspects. I'll admit that it would probably be tough for me to change my mindset on these since these definitions have been ingrained in me for 10-20 years. But, as always, my viewpoint doesn't necessarily reflect everyone else's viewpoint.