Hi, do you mean you use it as your Firefox Account email address? At some point, you may need to verify your login and if you can't, that account will be locked out forever. So it's a good idea to keep backups of your data "just in case" rather than relying on Sync for recovery. This article has tips on backing up your Firefox data: [[Back up and restore information in Firefox profiles]]. If you meant the email address shows up or is used somewhere else, hmm, where??