Hi! Were you already using this email before, or are you setting it up now in Outlook 365?
If you were already using it, remove the current profile and create a new one.
- If your email is POP, back up your Outlook data file in Documents > Outlook Files.
- Press Windows + R > type control > Under View By, select Icons > Click Mail (Microsoft Outlook).
- Click on Show Profiles... > Select your profile > Remove > Restart your computer > Return to this menu and add a new profile.
- Select Manual setup or additional server types > POP or IMAP > Fill in the requested fields with your account information.
- Check with your email provider to see if the incoming and outgoing server settings, ports, or other important information have been modified.
- Click More Settings > Fill in more information under Outgoing Server and Advanced.
- Click OK > Next.
Some email providers require an application code instead of a password. If the problem persists, try generating an application code in Yahoo and using it in place of the password.