Your account’s email address is very important, as that is what allows you to log in, receive confirmation emails, etc.
Individual BlockFi accounts can update their email address directly from the Profile Settings tab which can be accessed while signed into BlockFi.
BlockFi Business accounts can update their email address by completing the attached form here.
Upon successful completion and review, your account will be updated accordingly and you'll receive an email once complete. This process should only take a few business days.