Change your SITE123 mailbox password and set it to forward emails to another mailbox.
Edit the Mailbox Settings
To edit your mailbox settings, follow these steps:
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.
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.