Your primary email address is the email Celo uses for all contact regarding your account, e.g. password recovery. You can also use it to log into Celo. Your primary email address remains the same even if you leave a workspace, or move to a new one.
This means that you can still receive emails from Celo after changes to your employment, or when you receive a new company email. Note that, in compliance with privacy and security laws, Celo will never send sensitive information like the content of your messages via email.