Gmail Address Not Found is a common error in Gmail that appears when the email address you entered does not exist or cannot be recognized by the system. This issue may occur due to a typo, a deactivated account, or incorrect domain spelling. To fix the problem, double-check the recipient’s email address, verify the spelling, ensure the account is active, and confirm there are no extra spaces or characters. If the issue continues, try contacting the recipient through an alternative method to confirm the correct email address.