The idea for the "Kindred Spirit" mailbox originated with a man named Frank Nesmith and a woman he was dating at the time. The couple installed the first mailbox in the 1970s on Tubbs Inlet, which separates Sunset Beach and Ocean Isle. Inside the mailbox, the couple put a notebook and pen for visitors, otherwise known as “Kindred Spirits,” to write whatever they wish.

When the mailbox became endangered by the migrating Tubb’s Inlet in 1983, Nesmith moved it to Bird Island. At that time, Bird Island was separated from Sunset beach by another inlet called Mad Inlet. Visitors to the mailbox would have to wait for low tide to cross or wade through the waters at high tide. Over the years, Mad inlet has filled in and now visitors from Sunset Beach can make the trip unimpeded.

The notebooks collected from the Kindred Spirits mailbox contain a wide variety of entries written by visitors from around the world. Some entries are anonymous while others are signed and dated. Visitors share their thoughts, writing words of happiness, sadness, anger and many other emotions. Entries range from the lighthearted to the most personal human experiences, detailing youth, love, marriage, divorce, death and much more.