If you are unable to use a Gmail account in the Email settings section of any Act4 Products, then you will likely need to disable the enhanced security features on your account.
To do this, please follow the steps below, or refer to the article provided by Google which can be found here: https://support.google.com/accounts/answer/6010255?hl=en
- Visit the following link: http://www.google.com/settings/security/lesssecureapps
- Log in to your Gmail account if prompted.
- Click on the Turn on option.