We would like to block the sender to send email to external domain, at the same time users should be able to send email to co-existence domain which on the same SMTP server, any solution for this would be very appreciated.
Sathish
Subject: SMTP Outbound Restriction with specific internet domain
Have a look at the Configuration document for your SMTP server There is a setting under Router/SMTP - Restrictions and Controls - SMTP Outbound Controls : Allow messages only to recipients in the following Internet domains or hostnames: