Avoid Email to Contact person

Dear SDN team,

I would like to know if there is a possibility to "avoid sending emails to a specific set of Contact persons" which are present in a Target group.

We want to avoid sending emails only to few contact persons. I have tried to use the "contact flag" available on the "status tab" for the Contact person screen.

Unfortutanately , emails flow to contact person even after enabling the "do not contact" flag.

Can someone please help me here ??

Regards

Dinesh