1.4. Email Server Tasks
The tasks performed by an email server running sendmail can be roughly broken down into the following categories:
Receive and queue email for delivery to other servers
Receive email and store it in the appropriate mailbox
Send locally generated email to other servers
The server may also run other tasks, such as allowing access to messages via POP or IMAP, but these tasks are unrelated to sendmail.
Most email servers perform each of the three aforementioned tasks, although some servers may perform one or two of these tasks far more frequently than others. The first task is representative of the workload handled by an email gateway. Large organizations often use gateways to provide a limited point of access for email to flow ...