docs/diploma

annotate thesis/tex/1-Introduction.tex @ 46:d3312a3b6e70

minor stuff; indention by tabs
author meillo@marmaro.de
date Tue, 14 Oct 2008 11:48:47 +0200
parents f789b659f094
children d52fa2350137
rev   line source
meillo@26 1 \chapter{Introduction}
meillo@42 2 \label{chap:introduction}
meillo@26 3
meillo@26 4 \section{History of electronic mail}
meillo@30 5 %TODO: have a quote from Bell Labs about email here
meillo@30 6 %FIXME: add references to text
meillo@27 7
meillo@30 8 Electronic mail (short: \name{email}) is a basic concept in \unix. On \unix\ machines, a lot of information is distributed by \name{system mail}, which is email sent by the operating system. Beside that, email is the common communication system between humans working on computers.
meillo@27 9
meillo@30 10 The \unix\ operating system supports email since 1979 through the \name{mail user agent} (\NAME{MUA}) \path{/bin/mail}. For transporting mail in between two systems, the \NAME{UUCP} protocol (for ``\unix\ to \unix\ copy'') was invented.
meillo@30 11 %FIXME: what about `uuxqt' and `rmail'
meillo@27 12
meillo@30 13 As generally known, the early development of \unix\ was not only made in the \name{Bell Labratories} of \NAME{AT\&T}. 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 14
meillo@30 15 This lead to a second \NAME{MUA} from Berkeley: \name{Mail} (with a capital `M'). Also, no \NAME{UUCP} network was set up at Berkeley but an own creation called \name{BerkNet} was used.
meillo@30 16 %FIXME: why? license issues? closed source?
meillo@31 17 %TODO: what about `mailx'?
meillo@27 18
meillo@30 19 Further more there was a third network type: the \NAME{ARPAnet}, based on the \name{transmission control protocol} (\NAME{TCP}).
meillo@30 20 %FIXME: where did it came from?
meillo@30 21
meillo@30 22 Each of the three network types could transfer email between different machines. The file transfer itself was made using \NAME{FTP}, but the higher layered logic of the transfer was different in each. For example was the addressing schema not the same: \NAME{UUCP} used a flat-style schema, while \NAME{ARPAnet} was hierachical.
meillo@30 23
meillo@30 24 Mail transport from one machine using one kind of network to a second machine using another kind was a problem. 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 25
meillo@30 26 It was around 1982, when Eric Allman, then a student at Berkeley, wrote \name{delivermail}. Its purpose was to transform email from one network to another. \name{delivermail} like its successor, the more flexible \sendmail, intermediated between the different networks. They were able to transform email messages from any network to any other.
meillo@30 27
meillo@30 28 Todays email structure is basicly the same as then. The major difference is the uniformity of the underlying network, which is nearly always the \NAME{ARPAnet}-based \name{Internet}. Most other differences are organized as extensions to the old model of electronic mail.
meillo@30 29
meillo@30 30 More information about electronic mail and its history can be found at:
meillo@30 31 %FIXME: add books and websites here
meillo@30 32
meillo@27 33
meillo@26 34
meillo@26 35 \section{Transporting mail}
meillo@31 36 %TODO: include definitions from others here (cites)
meillo@31 37 %TODO: when was the term ``mail transfer agent'' established?
meillo@27 38 The basic job of a \name{mail transfer agent} (or \name{mail transport agent}, short \NAME{MTA}) is to transfer/transport \name{electronic mail} (short \name{email}) from one host to another.
meillo@27 39
meillo@27 40
meillo@26 41
meillo@30 42
meillo@34 43 \section{\sendmail}
meillo@42 44 \label{sec:sendmail}
meillo@31 45 \name{sendmail} is the de facto standard for \name{mail transfer agents}.
meillo@27 46
meillo@27 47 % FIXME: is that true?
meillo@27 48 It was the first \NAME{MTA} and had no real alternative for a long time.
meillo@27 49
meillo@27 50 All other existing substitutes, which are mainly \name{postfix}, \name{exim}, \name{qmail} and the here regarded \name{masqmail}, mimic \name{sendmail}'s behavior. Especially, they all create a symbolic link named ``sendmail'' pointing to their own executable. This is because a lot of programs assume there is an executable called ``sendmail'' on every computer system.
meillo@27 51
meillo@27 52 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 53
meillo@26 54
meillo@30 55
meillo@26 56 \section{(a look at Windows)}
meillo@26 57