ICANN has made some recent changes to the process that you must follow to update the Registrant contact info in your account, including any changes to name, organization, email address on your domains.
When you update your Registrant info on a domain, this new process sends an email to the shopper email address, the existing email address being replaced, and the new email address for the Registrant contact. Either the shopper or the existing registrant email address AND the new registrant email address are required to approve the update. If these email addresses are the same, only one email and approval will be required.
You should be able to easily accomplish this task online by making changes in your ITEGY account, then logging into your email account and following the directions provided in the email you've received.