To avoid confusion with usernames, please make note of the following: Each main account (each cpanel account) has one main login for email that is the same as the cpanel account login. This login when used with a mail program must not have the @domain.com portion attached to the end of the username. Any e-mail accounts created through cpanel have a username of: username@domain.com. They must have @domain.com appended to the end of them to work in a mail program. If your e-mail program does not accept the @ symbol then try replacing it with a % symbol or a + symbol. (In the above text domain.com stands for the cpanel account's domain name.)