Stop unknown people from contacting you on snapchat?

By default, only your Snapchat friends can contact you on Snapchat. You may see messages from people in your phone’s Contacts if they reach out before adding you as a friend on Snapchat.

When you receive a message from someone who is not your friend on Snapchat, you can tap ‘Report or Block’ in the Chat to clear the conversation from your feed. The Snap chatter won’t know that you have hidden or blocked them. You can also disable messages from non-friends in your Settings.

Snapchat users can prevent random people from following/adding them. Above all else, it’s strongly recommended to turn off the ‘Quick Add’ feature. When opening the search page in the Snapchat app, the Quick Add section shows a list of people Snapchat thinks that users should add. Quick Add recommendations are based on someone’s contacts and users that are mutual friends. It’s a good tool to discover friends that someone may not have added yet, but on the flip side, Quick Add also exposes people’s usernames to an unknown group of individuals.