If you receive the error message "the user you are trying to reach is over quota" then most likely you have exceeded the capacity of your email hosting account. You can request a quota increase by opening a support ticket at: http://www.efashioncentral.com/support/
However, you will encounter the same error again soon unless you delete mail off of the server. If you use webmail at http://efcmailserver.com/ you can click on "Folder Sizes" to see folders that are consuming your space. It is best to delete mail that contains attachments.
If you use Outlook to retrieve your mail, be sure to have it delete mail off of the server after a short time. By default Outlook will delete mail immediately once retrieved but if this setting has been changed, check that it looks something like below: