This e-mail address, with the username the same as your hosting account, is also known as the "catch-all" e-mail address. In other words, if you have no e-mail accounts setup, this will catch every e-mail sent to anything@yourdomain.com for your retrieval. This will still work even when other accounts are created, which is especially useful if people incorrectly spell the first half of the e-mail address wrong, since you will still get that sometimes-important e-mail. This is the one e-mail account that is setup with your e-mail software with the username only (all other accounts use username@domain.com as the username in their mail software.) This is also the only webmail account that you have "instant" access to within your control panel without having to login first.