==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.5.-1
- Linux/BSD distribution name and version: CentOS 6
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Apache
- Manage mail accounts with iRedAdmin-Pro? iRedAdmin-Pro-SQL 2.4.1
- Related log if you're reporting an issue:
====
After set up enable throttling, user over quota send email like:

"This is the mail system at host mta02.xxx.xx.

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own text from the attached returned message.

                   The mail system

<user03@test12.xxx.xx>: Host or domain name not found. Name service error for
    name=test12.xxx.x type=A: Host not found"

How to change content user03@test12.xxx.xx over quota throttling.

Thanks your help.