Version 8

Suppressing the Notification

Disable all the Carriers at once
This is the best approach if you have to test the specific Notification, instead of a single Carrier.
To do this, you should use the filter:
add_filter( 'notification/should_send', function( $should_send, $notification, $trigger ) {
if ( $something ) {
$should_send = false;
return $should_send;
}, 10, 3 );
At this point, the Trigger doesn't executed the action() method so you cannot use the Merge Tags. If you rely on Merge Tags, suppress the Carrier instead.