Change your SITE123 mailbox password and set it to forward emails to another mailbox.
To edit your mailbox settings:
Go to your website Dashboard.
Click the Domain button and elect Mailboxes from the list.
Go to the Mailbox you want to manage and click the Edit button.
Enter a new Password in the text field to change it.
You can forward incoming emails to a different email by checking the Forward emails to a different mailbox checkbox and entering the destination email.
Do not forward to the same email that you just created (i.e., the email email@example.com cannot forward emails to firstname.lastname@example.org).
Check the Keep a copy of the message in the mailbox checkbox if you want to keep a copy of the email before forwarding it to the other email address.
Click Apply to save the changes.