After the WeChat group was sent, I saw that the message was not sent successfully.

1. First open WeChat and click Settings, as shown below.

2. After entering, click General, as shown in the figure below.

3. Click General Function, as shown in the figure below.

4. Find the group assistant under the enabled function.

5. Then click Start Mass Sending in the opened page, as shown in the figure below.

6. Select the recipient, enter the content to be sent, and click Send, as shown in the figure below.