If you have a Gmail account you have not used in a few years, it’s likely to be deleted. Starting next month, in December, Google will delete accounts that have been inactive more than two years. The reason? Security. Older accounts are 10x less likely to have two-factor authentication activated. And they often use old or compromised passwords. If you have a favorite Gmail account, definitely login, change the password, and activate two-factor authentication.

Source: https://blog.google/technology/safety-security/updating-our-inactive-account-policies/