Old-System Email - The term Isomeris uses to refer to the email system we all know and use since the seventies, before the arrival of EmailXT. RFC's 821/822 and 1939 describe this standard. Outlook, Thunderbird and Eudora are examples of well-known old-system email clients.

R

Reference Application - An application that is used to test others, to make sure they meet the minimum standard requirements.