I just want to send fan mail to a person but I only want that person to see it. Of course, they are not following me.
Twitter would not seem to be the right venue for that. According to Twitter support, direct messages can only be sent to:
- someone you follow
- a group conversation (where all the messages are seen be the group, and only the group, without needing everyone to be following everyone else)
- some accounts change a setting that allow anyone to send them a direct message
Unless the account has used the option mentioned in point 3 above, direct messages would appear to be unusable.
The other way to direct a message to someone on Twitter, a "mention" (where you tweet a message with the username prepended with
@, is not private, although it's not fully public. Such messages appear:
- on your profile page of public tweets
- on the recipient's Mentions and Notification tabs (accessible only by the recipient)
- on the home timeline view of anyone following the recipient
Unless you can convince your recipient to start following you, it would seem that you'll need to find some other avenue of contact.