Yahoo made some changes to how they sync business Yahoo emails:

1. First, please make sure that your Imap settings are turned on within your email settings (use this link):

2. Second, please log-in to your Yahoo business account and set up an app password so NowCerts is able to connect to the account:   

  • Use these settings to connect your Yahoo business email. I will also include an example screenshot.

The description you'll see: 

Enter this information:

Incoming server:
Port: 993 with SSL

Outgoing server:  
Port: 465 with SSL  
Use authentication

Username: [your full business email address]

Password: [your app password]

(Learn more about app passwords.)