I sell an app, and people often tell me they can't find their license code anymore. More often than not, these are from Gmail addresses. This may be just becaus

I sell an app, and people often tell me they can't find their license code anymore. More often than not, these are from Gmail addresses. This may be just because Gmail is popular. But it's still baffling how Gmails original proposition was that you would always have an archive of all your mail and could search it instantly, yet all these people can't find the email with a license code for an app.