This is (although I didn't update it in 7 years) a plugin I made for WordPress when I was looking for plugins that could store a simple contact form message into the database instead of mailing me every time someone wanted to get in touch though the website.
It was well received (I guess) and after some weeks after the launch it got like 4,000+ downloads and active installations. After that, and noting some troubles, I decided to launch a fix including some features like reCAPTCHA, async behavior, CSS customization, and much more. It got until the version 2.0, with features like replying the messages straight from the admin panel, a new reCAPTCHA version and some more.
Between other features I can count, there were mail notifications that summed up and were sent depending of the picked frequency: like once per day, per week or month (using the by-then-new 'cronjob' feature given by WordPress).
I left it unattended, mostly because of work and study. But people trusted the product anyway, even without updated support. According to WordPress repository there are copies still being downloaded. Weird.