A test email address allows you to test G Suite by receiving email. Once you verify domain ownership, each user in your domain will be assigned a test email address to receive mail. Test email addresses have '.test-google-a.com' appended to the end. Your test email address will look like this: user.name@your_domain.com.test-google-a.com.
Use a test email address
You don't use test email addresses for sending mail. You can use them to test mail delivery or set up a pilot for your users. You can continue using them for as long as you need. Once you verify domain ownership, you can send mail from your G Suite email account. Mail sent from your account won't include test-google-a.com.
Remove the test email addresses when you're done with them
To remove the test email addresses for your users, follow the instructions to remove the domain alias your_domain.com.test-google-a.com.
Note: Unlike domain aliases you add yourself, you can't remove the test domain alias. De-activating it stops users from receiving email at their test email addresses.