Tumblr’s feature that allows followers to submit posts to a blog is called Submit.
Submit lets a blog owner invite contributions from readers, either for publication as submitted content or for review before appearing on the blog. The feature is controlled by the blog’s settings, so not every Tumblr blog accepts submissions.
Submit is different from Tumblr’s messaging tools. A user can send a question through a blog’s ask function, while a submission is intended to become a post on that blog. Tumblr has also offered private messaging and fan-mail-style features, which can cause confusion because all of them involve communication between users.
The feature fits Tumblr’s broader culture of collaborative blogging: individual blogs often act as themed communities, collecting art, writing, recommendations, memes, and fan contributions. Depending on the blog’s rules, submissions may be edited, rejected, answered privately, or published with the contributor’s identity attached.