You can publish blog posts to someone else’s Tumblr blog if the owner of the blog has enabled submissions for viewers in the blog settings.

However, Tumblr also offers other ways to interact with the blog owner and her followers.

You can reblog and reply to posts, if enabled.

You can also ask the blog owner questions using the Ask Me Anything feature.

Finally, if you have been invited to contribute to a private group blog, you can publish posts as a member or administrator, depending on your level of access.