Dread Mailbox is drama created, based on the calls and stories of viewers, recorded through phone number 1855-0666. It can be real experiences, stories heard somewhere, or imaginary ghost stories. Number is still active, and network encourages to continue sharing stories, using it. Each of the people whose story was featured in the series was awarded an airpod.
(Source: Youtube site of 스튜디오 룰루랄라- studio lululala)