==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.84
- Linux/BSD distribution name and version: debian 8 jessie
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  mysql
- Web server (Apache or Nginx): nginx
- Manage mail accounts with iRedAdmin-Pro? no
- Related log if you're reporting an issue:
====

This is block to send outside domain but and send inside domain only.

Black List all

python /opt/iredapd/tools/wblist_admin.py --outbound --account username@localdomain.com --add --blacklist @.

White list local domain

python /opt/iredapd/tools/wblist_admin.py --outbound --account username@localdomain.com --add --whitelist @localdomain.com