If you enable two-steps verification in your Google gmail account, you need to create an app password to continue sending your messages with Shop'NCook software.
To do that, proceed as follows:
Enable two-step verification if it is not yet enabled. You can enable it by going to the settings Sign-in & security, selecting "Signing to Google" and then "2 Steps Verification".
Add an app password by selecting "App passwords" in the "Sign-in and security" settings. Select "other app" and input "Shop'NCook Menu" or "Shop'NCook Pro" as app name.
Input the automatically generated password into Shop'NCook software e-mail settings.
Restart Shop'NCook software before sending e-mails.