Please provide a way to hide the main account id.

The main account id is the id we use to login our account into this service.

For privacy it MUST be able to be hidden and be separate from other email addresses we use to send an email.

Because an id is valuable information just like passwords, spies often make use of it.

The main id should be treated as a vulnerability.

You have to give a user a warning at least or an option which allows a user to disable the mail address that includes the main account id, so the user may not accidentally expose their main id sending an email to someone else.