Yes, we can use domain based Email in Google Cloud IAM
Actually there are 2 types of (Google) user accounts: [your-name]@gmail.com and those created by an organization for its users email@example.com. For example, Google uses Google identity internally and so Googlers have emails [their-name]@google.com.
When you create a Google Cloud Platform project, anyone with a Google account may be added to it. Whether their Google account is firstname.lastname@example.org or an account created by their employer for them.
The only time your users will receive an email from you when you add them to a Google Cloud Platform project is if you make them project owners. This is because, ownership requires acceptance of Google's Terms of Service. Other types of users will be added without receiving an email (from Google about it) but will be able to access your project's resources.
Hope this is helpfull!!