[exim] How to suspend user to send emails, even to local dom…

Hi,

I need to set up two email accounts on one domain:
- so that these 2 accounts only are able to receive email
- and never be able to send (or reply to) any email, both for local
domain or other domains whatsoever

The other accounts on this domain must be able to receive and send
emails , both for local domain or other domains as well.

How can I achieve this?

Should I create a rule?

Or should I create a limit to these 2 users, of sending zero emails?

Regards,
Pedro