Group Creation

Is it possible to create groups inside the server so that only the particular users in a group can send emails to outside. Or else is there any way so that some users can send emails only to the same domains. or few domains



Howdy -- unfortunately, there isn't a Virtualmin supported way of doing that.

Postfix does support that, but the configuration can be somewhat complex, and you'd have to configure it manually.

You can read about how to do that here, in the section named "Restricting what users can send mail to off-site destinations":

Before you make any changes to your Postfix config, I'd suggest making a backup of the config file first so that you can easily revert to a working copy if something doesn't work properly.