When you're not busy blogging and reblogging on Tumblr, the platform also offers a user-to-user messaging service like Twitter's Direct Message system or the Messages component of Facebook. There are two types of messages: Asks, which are questions, and Fan Mail, which work like a short email system. Fan Mail keeps messages private, while Asks can be kept private or made public.

Fan Mail

You can use Fan Mail to send messages to other Tumblr users from your dashboard, your inbox or blog pages. Messages can be sent to any blog you've been following for at least 48 hours. There are no length limits to Fan Mail messages, and you can include links if you wish to. There are two types of paper and three styles of writing to choose between, and you can send up 500 messages per day. Fan Mail is kept private between the sender and the recipient and cannot be disabled.

Asks

Asks are short questions sent to Tumblr blogs through the dashboard or the blog itself. Like Fan Mail, Asks are delivered to the inbox page. When replying to an Ask, there's the option to reply privately (to the sender's inbox) or publicly (in which case the question and answer are posted on the recipient's blog). It's up to each blog owner to decide if Asks are enabled or disabled, and whether to allow anonymous questions. If an Ask is submitted anonymously, it must be replied to publicly rather than through the inbox system.

Submissions

While they are not secret messages in the strictest sense, Submissions are also part of Tumblr's inbox system. Submissions are posts submitted by visitors to your blog, and you can choose whether or not to publish them. Like Asks, Submissions can be enabled or disabled through the Tumblr blog settings, and it's up to the owner to decide to enable them. Submissions cannot be replied to privately: they must be either published on the blog in question or ignored.

Managing your Messages

You can access all of your incoming Asks, Fan Mail and Submissions by clicking on the envelope icon at the top of the Tumblr dashboard to access your inbox screen. Next to each message are options for replying to or deleting particular messages. If you reply to Fan Mail, your response is kept private; if you respond to an Ask, you have the option to post the reply on your blog or answer privately (unless the question has been asked anonymously, in which case it must be posted). For Submissions, you have the option to publish or remove each post.