iRedMail is really well configured to best practices, but too strict for many other mail servers.   I'm hosting mail for my brother and some people have misconfigured their mails server (eg, reporting .local addresses) and I want to tailor NDRs with more helpful information (I'm not relaxing the policies).   I've seen some examples for a custom bounce.cf, but these seem to be very non specific and lacking in detail in their error messages.

Is there another file for NDRs for more specific error information?

==== Required information ====
- iRedMail version (check /etc/iredmail-release):  latest
- Linux/BSD distribution name and version:  ubuntu 14.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Apache
- Manage mail accounts with iRedAdmin-Pro? Nope
- Related log if you're reporting an issue:
====