Last Updated: Jun 4, 2021
If you are using a Gmail account, change the security settings of the account.
Click here to know more about the steps.
After you change the settings, refresh the Task design page where you are validating the email configuration and validate the credentials again.
This error occurs when you do not provide the Outgoing protocol and Outgoing server in the Configurations for Email Sender node. Click here to know more about how to specify the Configuration.