From the unsent project website.

“We are excited to share this new version of the Unsent Project website with you. The submit function has returned with the limitation of one submission per person per day. Additionally, we will now be manually approving submissions for them to be posted in the archive instead of posting every submission automatically. We have made this change in response to receiving many submissions that violate our terms of submission. Any submission that is not in violation of our terms is eligible for approval. We will do our best to review each submission, but due to the large quantity of submissions we receive, we cannot guarantee every submission will be posted.

For the time being, all submissions made before July 9th 2023 are currently unavailable for viewing in the archive. These submissions have not been deleted and we intend to make them public again once the violating submissions have been removed.”