Hello billy wang1,
Thanks for using Microsoft products and posting in the community.
I understand that you are unable to add a 163 email as an IMAP account.
Please note that you cannot directly add a 163 email to new Outlook using your account password. You may need to create an app password.
First, you need to log in to your email on your webmail. Choose POP3/SMTP/IMAP in the Settings.
Follow the steps provided by your email service provider to enable IMAP service.
After enabling, generate an app password according to the steps provided by the email provider. Then you can use this app password to add the IMAP account to Outlook.
Please feel free to let me know if you need any further assistance.
Best Regards,
Zachary.W - MSFT | Microsoft Community Support Specialist