Suddenly, I had over 7,000 WordPress Feedback Spam entries. Feedback is JetPack’s Contact Form. Crazily, Feedback doesn’t have a bulk Empty Spam button like Comments does. I LOVE Comments’ Empty Spam button!

First, log in to phpMyAdmin and take a backup of the database.

Then, click on the SQL tab and run the below Queries. If you’re like me, you’ve changed the wp_ table prefix to something unique, like runningunderwater_posts. Be sure and use your unique table prefix when typing in the Queries.

Type this in to make sure you’re targeting the correct Feedback POSTS tables:

[code]SELECT * FROM wp_posts WHERE post_type=’feedback'[/code]

Then, run this to delete the Feedback tables:

[code]DELETE FROM wp_posts WHERE post_type=’feedback'[/code]

Next, type this in to make sure you’re targeting the correct Feedback POSTMETA tables:

[code]SELECT * FROM wp_postmeta WHERE meta_key LIKE ‘%feedback%'[/code]

Then, run this to delete the Feedback tables:

[code]DELETE FROM wp_postmeta WHERE meta_key LIKE ‘%feedback%'[/code]

Source: How to Delete Feedbacks from JetPack Contact Form – WordPress Den

WARNING: this solution targets ALL Feedback entries, not just spam.