5.1. Why Design?

In designing a Sendmail configuration, we must take into account the overall design or philosophy behind our company's, campus's, or facility's e-mail system. So, before we can design and build our Sendmail configuration here (and we hope to do much of this from already existing bits and pieces), we will discuss the design issues associated with mail distribution systems on a network within an organization.

5.2. Mail Distribution Systems

The simplest way of designing your mail distribution system is for each host each discrete computer node to make a connection to any other host for which it has mail. Thus, if Anne on host cognition.frobozz.com wants to send mail to Eric on grizzly.wossamotta.edu, Anne's host establishes a connection to Eric's host and the mail is transferred (see Figure 5-1). This works well, but not in all cases.

Figure 5-1: Point to Point

What if Anne's machine and Eric's machine speak different network protocols (e.g., IP/TCP vs. DECnet)? What if Anne's machine expects RFC 822 mail headers and Eric's expects X.400 headers? Or what if Eric's machine isn't often connected; say it's a notebook personal computer he carries around from place to place? Or what if either or both of Anne's and...