Short Answer 
To DM someone on Discord without adding them as a friend, you must first be a member of the same server and ensure their privacy settings allow DMs from server members. After confirming these settings, locate the user’s profile in the member list and click the ‘Message’ button to start chatting.
Step 1: Join the Same Server
To DM someone on Discord without adding them as a friend, you first need to be a member of the same server as the person you wish to message. This creates a shared space where communication is possible. Ensure that the server is one where you both have access, either publicly or through an invitation.
Step 2: Check Privacy Settings
Once you’re on the same server, verify that the recipient has their privacy settings configured to allow direct messages from server members. If they have restricted DMs, you won’t be able to message them unless they change this setting. It’s essential for ensuring that your communication can go through seamlessly.
Step 3: Send a Direct Message
After confirming the necessary settings, locate the person’s username in the member list of the server. Click on their username to bring up their profile. If they permit direct messaging, you’ll see a ‘Message’ button, which you can click to open a chat window and start typing your message.