When setting up your Yahoo email to get an email alert, if the email test fails, you will need to generate an app password in your Yahoo email account and use this new app password as your Yahoo email password.
Please kindly refer to the steps below to fix the issue.
1. Log in to your Yahoo email account and go to >Account information like the picture below.
2. Go to Account security
3. Go to Generate APP password or Manage APP password.
4. Select your APP>> other app>> manually input" Reolink app"
5. Click" Generate" and it will generate a password like a picture below, please use this new app password as your Yahoo email password to set up your Yahoo email to receive an email alert.