The ‘postmaster’ account is an email account which is preconfigured by and has, by default, the same password as the domain: such account cannot be deleted nor renamed, but it can be used as a normal email account.

It is given in addition to the other 5 email addresses, therefore with each domain name that you register you get 6 email accounts.

If you change the password of the postmaster account you will also change the password to access the
Email Control Panel.