This script was initially released in 2010, and was living in a messy GitHub repository.

After some years, the script basically outgrew its initial intent, and moved in 2013 to its own repository.

It then continued to be updated as a stand-alone script before being properly packaged into the current form. The last known working version of the stand-alone script is available in the legacy branch.

The project lived under the name maildir-deduplicate from 2014 to 2020. It was renamed to mail-deduplicate in 2020 following the addition of mbox support alongside maildir sources.