ABSTRACT
In addition, you may have noticed that my description of the e-mail relay process stopped at the recipient's Internet mail server, or MTA. The reason for this is that a user agent can employ different methods to access, or retrieve, its e-mail from the MTA. For instance, the majority of companies rely on proprietary e-mail packages, such as cc:Mail, to handle e-mail operations on the local network. And individual users often use e-mail applications offered by online services such as CompuServe and America Online, which you can also consider proprietary e-mail programs. In both cases, the proprietary system acts as the last leg between the final MTA and the recipient UA.
