Could not connect to SMTP host: smtp.163.com, port: 587, response: -1

This error message usually indicates that there is a problem connecting to the SMTP server at smtp.163.com on port 587. Here are some potential reasons and solutions:

1. Firewall or network issues: Make sure that your firewall or network settings are not blocking the connection to the SMTP server. Check with your network administrator or IT department to ensure that the necessary ports are open.

2. Incorrect SMTP server settings: Double-check that you have entered the correct SMTP server address (smtp.163.com) and port number (587) in your email client settings.

3. Authentication issues: Some SMTP servers require authentication before allowing you to send emails. Make sure that you have entered the correct username and password for your email account.

4. Server downtime: It's possible that the SMTP server is temporarily down or experiencing technical difficulties. Wait a few minutes and try again later.

If none of these solutions work, you may want to contact your email service provider for further assistance.