This setting allow to determine who will be notified in case there are several SonarQube issues matching filter settings found in particular commit.
An e-mails sent to recipients will contain review information: title of review and list of comments (issues). Recipient settings:

* None - No one;
* Owner - Owner (i.e. author of the commit);
* Owner and Reviewers - Owner (i.e. author of the commit) and all Reviewers (people who was added to reviewer list of the commit);
* All - everyone in the project list.