Do I have to add friends to send messages to others?

First, the method of adding:

Open the mobile client of Baidu Post Bar and click on the contact. If you are adding a friend you don't care about, click "Add Friend", directly enter the friend id, click Search, enter the friend's personal homepage, and click Add Friend. Of course, you can also add friends by clicking on their avatar or id in the post bar. If you are concerned, you can click "new friend" in the contact column and add it to your friend's right.

Second, the method of agreeing to supplement:

Download the client, click on the contact list, find the new friend column, and then you can pass the verification.