Your wallet identifier (ID) is one of the credentials required to log into your wallet; for this reason, it is incredibly important to keep it adequately secure. Keep in mind that anyone who gains access to your wallet gains complete control of your digital assets.
We recommend storing your wallet identifier in a secure, preferably offline, location. If you use a password manager for keeping track of your credentials, you can also store it there. Because we send you an email containing your identifier when you sign up for a wallet, it is likewise important to keep that email account secure. At minimum, we recommend having a strong password and a method of two-factor authentication on your email account.