As part of a new purge of dormant accounts announced in May, Google now says if you haven't used or signed into your account for at least 2 years, it may delete the account and its contents.
For Google users, this means not only losing an email address, but any photos, emails, Google docs and notes that were saved in a Google account.
However, you would first have to completely forget your Google account for two years and then ignore "multiple notifications" that your account is risking deletion.
Free online accounts that you no longer use but still want to keep are generally at risk of being deleted if you don't log in from time to time, and a calendar reminder to log in once a year can make sense if the account is important.
The periods of inactivity that need to elapse before you receive warnings that your account will be deleted. While a Microsoft or Google account may be inactive for a whole two years, an account with X, formerly Twitter, requires you to log in at least every 30 days.