Multi-level throttling

==== Required information ====
- iRedMail version: 0.8.6
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: Centos 6
- Related log if you're reporting an issue:
====

I'm wondering how the throttling works with iRedAdmin Pro:  if for example a limit is set per user and another limit per domain, do both limits apply?  i.e. 5 domain users @ 5 emails/minute and 10 emails/domain/minute... does 1 rule just overwrite the other or does it work like mailbox sizes where both limits apply?

Cheers
Dominique