@cenonmin_645741266128992 Check point 3 in this link https://support.reolink.com/hc/en-us/articles/360015302994-How-to-Improve-the-Image-Quality-of-Reolink-Cameras/
In email attachment you can only find the video in fluent mode. The main reason has to do with the email size.

Ok, I got it. Thank you for your support.

Why cannot I change the quality of the video attachment in email notifications?

The quality is very poor and I want to set it to the raw quality saved in the SD Card.

The quality of the video attachment in email notifications is determined by the email client you are using. Some email clients may allow you to change the quality of the video attachment while others may not. If you are using Gmail, you can change the notification settings for your account to receive notifications for new mail or important mail only. However, if you want to send a video through email with better quality, you can use Google Drive to upload and share the video with your recipient.