You may receive an error such as

----- The following addresses had permanent fatal errors -----
(reason: Can't create output)

This message is because the account in question is over-quota.

You can increase the available disk space of the user through the BlueOnyx control panel by entering the BlueOnyx control panel and from the Site Management tab, click the "i" Edit icon for the domain name. Then click to edit the user from the user list and increase the available disk space for the account.