meillo@26: \chapter{Introduction}
meillo@42: \label{chap:introduction}
meillo@26: 
meillo@26: \section{History of electronic mail}
meillo@30: %TODO: have a quote from Bell Labs about email here
meillo@30: %FIXME: add references to text
meillo@27: 
meillo@47: Electronic mail\index{electronic mail@electronic mail (email)} (short: \name{email}) is a basic concept in \unix.
meillo@47: On \unix\ machines, a lot of information is distributed by \name{system mail}, which is email sent by the operating system.
meillo@47: Beside that, email is the common communication system between humans working on computers.
meillo@27: 
meillo@47: The \unix\ operating system supports email since 1979 through the \name{mail user agent} (\NAME{MUA}) \path{/bin/mail}.
meillo@47: For transporting mail in between two systems, the \NAME{UUCP} protocol (for ``\unix\ to \unix\ copy'') was invented.
meillo@30: %FIXME: what about `uuxqt' and `rmail'
meillo@27: 
meillo@47: As generally known, the early development of \unix\ was not only made in the \name{Bell Labratories} of \NAME{AT\&T}.
meillo@47: But also the \name{Univerity of California at Berkeley} worked on their version of a \unix\ operating system, called \NAME{UCB} \unix, or \name{Berkeley} \unix.
meillo@27: 
meillo@47: This lead to a second \NAME{MUA} from Berkeley: \name{Mail} (with a capital `M').
meillo@47: Also, no \NAME{UUCP} network was set up at Berkeley but an own creation called \name{Berknet} was used.
meillo@30: %FIXME: why? license issues? closed source?
meillo@31: %TODO: what about `mailx'?
meillo@27: 
meillo@30: Further more there was a third network type: the \NAME{ARPAnet}, based on the \name{transmission control protocol} (\NAME{TCP}).
meillo@30: %FIXME: where did it came from?
meillo@30: 
meillo@47: Each of the three network types could transfer email between different machines.
meillo@47: The file transfer itself was made using \NAME{FTP}, but the higher layered logic of the transfer was different in each.
meillo@47: For example was the addressing schema not the same: \NAME{UUCP} used a flat-style schema, while \NAME{ARPAnet} was hierachical.
meillo@30: 
meillo@47: Mail transport from one machine using one kind of network to a second machine using another kind was a problem.
meillo@47: This showed up at Berkeley where some departments of the university had switched to \NAME{ARPAnet}, and some to \NAME{UUCP}, while the rest was \name{Berknet}.
meillo@30: 
meillo@47: It was around 1982, when Eric Allman, then a student at Berkeley, wrote \name{delivermail}.
meillo@47: Its purpose was to transform email from one network to another.
meillo@47: \name{delivermail} like its successor, the more flexible \sendmail, intermediated between the different networks.
meillo@47: They were able to transform email messages from any network to any other.
meillo@30: 
meillo@47: Todays email structure is basicly the same as then.
meillo@47: The major difference is the uniformity of the underlying network, which is nearly always the \NAME{ARPAnet}-based \name{Internet}.
meillo@47: Most other differences are organized as extensions to the old model of electronic mail.
meillo@30: 
meillo@30: More information about electronic mail and its history can be found at:
meillo@30: %FIXME: add books and websites here
meillo@30: 
meillo@27: 
meillo@26: 
meillo@26: \section{Transporting mail}
meillo@31: %TODO: include definitions from others here (cites)
meillo@31: %TODO: when was the term ``mail transfer agent'' established?
meillo@47: The basic job of a \name{mail transfer agent} (or \index{mail transport agent|see{mail transfer agent}}\name{mail transport agent}, short \NAME{MTA}) is to transfer/transport \name{electronic mail} (short \name{email}) from one host to another.
meillo@27: 
meillo@27: 
meillo@26: 
meillo@30: 
meillo@34: \section{\sendmail}
meillo@42: \label{sec:sendmail}
meillo@31: \name{sendmail} is the de facto standard for \name{mail transfer agents}.
meillo@27: 
meillo@27: % FIXME: is that true?
meillo@27: It was the first \NAME{MTA} and had no real alternative for a long time.
meillo@27: 
meillo@47: All other existing substitutes, which are mainly \name{postfix}, \name{exim}, \name{qmail} and the here regarded \name{masqmail}, mimic \name{sendmail}'s behavior.
meillo@47: Especially, they all create a symbolic link named ``sendmail'' pointing to their own executable.
meillo@47: This is because a lot of programs assume there is an executable called ``sendmail'' on every computer system.
meillo@27: 
meillo@27: Besides being the ``standard'', \name{sendmail} probably is the most scalable and powerful solution for transfering emails and definatly the most flexible one.
meillo@27: 
meillo@26: 
meillo@30: 
meillo@26: \section{(a look at Windows)}
meillo@26: