Try logging in to the account you want to verify emails without actually sending an email. If the entered email address doesn't exist, Google will inform you. In free email accounts, you will see the email vendor they use. For instance, @gmail.com, @outlook.com, or @yahoo.com.

Go to http://accounts.google.com/signin/usernamerecovery and enter any email accounts or phone numbers that you've had for a while and which may have been used as recovery info. The “find your email” page can help you locate any forgotten Google accounts.

How do I trace the owner of a Gmail account? If a person used their real name to set up their Gmail account, you can use Google Calendar to find out the owner. Use the “share to specific people” option, then click “add people.” Enter the email address, and the owner's name and profile picture will appear.