If you received only one email message with your customer number, it's possible that someone entered the wrong information while trying to manage their account. This may have triggered the system to send your customer number to you, instead of that person getting their customer number sent to them. If this is the case, you can ignore the email.
However, if you receive multiple copies of this message in succession, someone may be trying to access your account. In this case, you should immediately log in to your ITEGY account, confirm that your account information is correct, and change your password to prevent unauthorized access to your account.