I could have sworn that there was a Domain Size Limit Exceeded System Message like there was for Mailbox Size Limit Exceeded.

We offer domains limited space (30GB) but unlimited accounts/aliases/groups. Many of those domains will manually set their primary domain administrator email account at '0' Unlimited (up to the domain max). When their account(s) reaches or exceeds that 30GB domain size limit neither the account user, nor their domain admin, are receiving any System Messages alerting them of this.

Also, wasn't there a System Message for both nearing Mailbox Size Limit and nearing Domain Size Limit? Because these would be really useful to have.