When adding an email address to a mail client, are you positive that you have the correct username and password as well as all the right server settings? Double check the email settings for “Less secure apps”.
The setting should be relatively similar for any email provider:
- Open your email settings online through the browser. Look for “Security settings” and there should be an option to toggle ”Less secure apps” on or off.
- Turning this on will allow you to connect the email account through your mail client.