Setting up the transport agent is perhaps the most crucial mail-related
job presented to the system administrator. There are a variety of
transport agents available on Unix systems, but
sendmail is by far the most widely used.
According to current estimates,
sendmail handles over 75% of all Internet mail traffic (Unix and non-Unix
alike). Other transport agents used on Unix systems include Postfix,
exim. We will consider
sendmail and Postfix here.
package is a very powerful facility, capable of
handling email from the moment a user submits a message from a mailer
program, transporting it across a LAN or the Internet to the proper
destination system, and then finally handing it off to the delivery
agent, which actually places the message in the user’s mailbox. In
fact, because the package includes a delivery agent program, the
facility as a whole can handle every aspect of electronic mail except
composing and reading messages and retrieving them from message
sendmail is also a
well-proven facility, and, at this point, is quite secure, provided
that it is configured properly.
There are commercial and free versions of
sendmail. The commercial versions, developed and sold by Sendmail, Inc., include additional features as well as easy-to-use graphical interfaces, integration with other related commercial products (e.g., virus-scanning software), and technical support. Vendor-supplied versions ...