As you know, if you're a Twitter user, you can send a direct message (DM) to any of your contacts by starting the tweet with a d followed by their name. So to contact me privately, you would tweet the following: d philbradley text text etc. Until now however you have only been able to send DMs to people that you are following and they are following you back. However, Twitter is now rolling out a new feature, which allows you to get DMs from anyone, not just those that you have a relationship with. You can of course block the feature as well. In order to check it, you need to go to your settings panel in Twitter and choose Security and Privacy:
Scroll down to the bottom of the page:
Then either tick or untick the Direct Messages box, and you're done!