After release 1.00.18.140 it is possible to prevent communication with candidates (or contacts) based upon their Status.
e.g. You may decide to prevent communication with any candidates who have their status set to "DNU"
After release 1.00.18.219 the feature also takes into account communication when you try to contact a Candidate from the [Contact] workbench.
How It Works
If you attempt to click on the email/phone number for a candidate who is at a blocked status the system will display a message box explaining why the communication is blocked.
In order to allow communication with the candidate you will need to change their status to another which does allow communication.
Note: The communication blocking by Status overrides any setting for communication which have been set in the Consent Centre in the Data protection manager (padlock) - see below:
The Block/Allow column shows (i) to indicate the communication is blocked by STATUS and clicking the (i) will show a pop-up message to that effect.
The Consent Centre needs to be turned on.
(Parameter GDPR, Flag(4) - Enable consent Centre Tab in Padlock )
To block communication for a particular status two new code tables have been added.
Stop Status (Cand) 
Stop Status (cont) 
You just need to add the relevant Status Codes to each of these tables.
Maintenance > Setup > code Tables
Select system area C - Contact Management, then choose the relevant code table.
Add the Status code you want to block, then press [OK]
Any blocking which has been applied based upon status only affects the specific record.
e.g. If the Candidate record for Miss Charley Trumpet has been set to a Status of DNU, then communication will be blocked from the candidate record.
However => If you used the 'Head' icon at the top of the screen to open the associated Contact Record then it would be possible to communicate from here, including details from the
e.g. Communication from the Candidate record (below) is blocked.
But.. If you open the Contact record (using 'Head' icon) then communication IS allowed and choosing the 'Personal' tab would allow communication to any of the displayed numbers.
To block communication with the contact record you would need to set the status for the contact record <OR> use the Padlock icon at the top of the contact record to manage this via the consent centre.
This may change with a future update and the details from the Personal Page of the contact record may be linked to (and prevented by) those on the associated candidate record.