Nowadays we’re very accustomed to recording and hearing the sound of our own voices. But in the 1930s many people were doing it for the first time. And a surprising trend began. People started sending their voices to each other, through the postal service. It was literally: voice-mail.

We recently combed through a large collection of early voicemail at the post.org">Phono Post Archive, and we discovered that many of these audio letters are about the same thing: Love.