If you are getting this error on your website, what this means is that your hosting account has exceeded it's monthly bandwidth limit. Bandwidth are calculated on monthly basis. Bandwidth is the amount of traffic coming to your website. Your domain bandwidth is made up of HTTP, SMTP, FTP and POP3 traffic.
To resolve this:
1.) You will need to upgrade to the next package ( which has a larger bandwidth ).
2.) Wait till the end of the month, when the bandwidth will reset back to 0 for a new month.
