First, you need to make sure that the person with the recipient role is set up and their email address is correct. It is also necessary to check that the recipient is there in the context.
If all of the above is correct, you have the customization at your disposal by accessing the environment as an administrator, in the notification configuration section where you will find a specific section for this parameterization.
But, our recommendation is to whitelist @globaleaks.org on your site and try again.
For more information, you can access the website of the Ethics Mailbox