1.1 --- a/thesis/tex/1-Candidates.tex	Sun Oct 19 17:58:41 2008 +0200
     1.2 +++ b/thesis/tex/1-Candidates.tex	Sun Oct 19 18:00:01 2008 +0200
     1.3 @@ -1,8 +1,10 @@
     1.4  \chapter{\unix\ \MTA{}s}
     1.5  
     1.6  This chapter introduces a group of \mta{}s.
     1.7 -These will be presented to the reader in a short overview and with the most important facts.
     1.8 -The next chapter will show a comparison of the candidates in several disciplines.
     1.9 +The selected group will be delimited against other groups of \MTA{}s, which are described as well.
    1.10 +
    1.11 +The chosen programs will be presented to the reader in a short overview and with the most important facts.
    1.12 +The next chapter will show a comparison of these programs in several disciplines.
    1.13  
    1.14  
    1.15  \section{Types of \MTA{}s}
    1.16 @@ -16,32 +18,44 @@
    1.17  Others have have every feature you can think of.
    1.18  And maybe there are some that do nothing else, but transporting email.
    1.19  
    1.20 +Here are groups of \mta{}s that will not be regarded in the following chapter.
    1.21 +% Prof: briefly discuss the border between small MTAs (sendmail, masqmail) and state-of-the-art mailservers (postfix) and groupware (notes, exchange): give usecases.
    1.22  
    1.23 -\section{The ones not regarded here}
    1.24 -The candidates for the competition in the next chapter are a subset of the \MTA{}s available.
    1.25 -Comparision between totally different programs (apart of one function) makes not much sense.
    1.26 -One would not use a program for a job it is not suited for.
    1.27 -Therefor \mta{}s that are rarely similar to \masqmail\ are not regarded.
    1.28 +\subsection{Relay-only \MTA{}s}
    1.29 +This is the most simple kind of \MTA. They transfer mail only to defined \name{smart hosts}\footnote{\name{smart host}s are \MTA{}s that receives email and route it to the actual destination}. \name{Relay-only} \MTA{}s do not receive mail, they only send it.
    1.30  
    1.31 -The first group of programs to sort out are the so called \name{groupware} programs.
    1.32 -These provide a whole lot of functions, including mail transfer, file storage, calendars, resource management, instant messaging and more.
    1.33 +Most \MTA{}s can be configured to act as such a forwarder. But this is usually an additional functionality.
    1.34 +
    1.35 +One would use such a program to give a system the possibility to send mail, without the need to do lots of configuration. In a local network, usually the clients are set up with such a forwarder, while there is one \name{mail server} that acts as a \name{smart host}. The ``dumb'' clients send mail only to this one \name{mail server} which does the ``real work''.
    1.36 +
    1.37 +Examples for that group are: \name{nullmailer}, \name{ssmtp} and \name{esmtp}.
    1.38 +
    1.39 +
    1.40 +\subsection{Groupware}
    1.41 +Normally the term ``groupware'' does not mean one single program, but a suite of programs. They are build up a framework which can be populated with various modules that provide actual funktionality. These modules including mail transfer, file storage, calendars, resource management, instant messaging and more.
    1.42 +
    1.43 +One would use one of these program suites if the main work to do is not mail transfer, but providing communication and team working support for a group of people. The most common scenario are companies. They have \name{groupware} running to provide adequate services for their teams to work efficently. But home servers may provide \name{groupware} services for the family members also.
    1.44 +
    1.45  Examples for this kind of programs are: \name{Lotus Notes}, \name{Microsoft Exchange}, \name{OpenGroupware.org} and \name{eGroupWare}.
    1.46  
    1.47 -The second group are the \name{relay-only} \MTA{}s.
    1.48 -They transfer mail only to defined \name{smart hosts}\index{smart host}\footnote{\MTA{}s that receives email and route it to the actual destination}.
    1.49 -Most \MTA{}s can be configured to act as such a forwarder.
    1.50 -But this is normally an additional functionality.
    1.51 -Examples for that group are: \name{nullmailer}, \name{ssmtp} and \name{esmtp}.
    1.52  
    1.53 +\subsection{More limitations}
    1.54  Third, only \emph{sendmail-compatible} \MTA{}s will be regarded in the competition.
    1.55 -Hence all \MTA{}s not having a \emph{sendmail-compatible} interface or not offering it as a compatibility addon, will not be covered here.
    1.56 +Hence all \MTA{}s not having a \emph{sendmail-compatible} interface or not offering it as a compatibility addon, will not be covered here. %FIXME: give an example for non-sendmail-compatible
    1.57  The reason is the heavy reliance of \unix\ systems on the existance of a programs called \path{sendmail}.
    1.58  This has historical reasons. See section \ref{sec:sendmail} for further information.
    1.59  
    1.60  Further more, only programs with source code available are regarded. %FIXME: why
    1.61  
    1.62  
    1.63 -\section{The competitors}
    1.64 +\subsection{The ones not regarded here}
    1.65 +The candidates for the competition in the next chapter are a subset of the \MTA{}s available.
    1.66 +Comparision between totally different programs (apart of one function) makes not much sense. %FIXME: better words
    1.67 +One would not use a program for a job it is not suited for.
    1.68 +Therefor \mta{}s that are rarely similar to \masqmail\ are not regarded.
    1.69 +
    1.70 +
    1.71 +\section{The programs regarded}
    1.72  The programs remaining are \emph{sendmail-compatible} ``smart'' \MTA{}s that do not offer masses of features unrelated to mail transport.
    1.73  
    1.74  For the comparision, five programs of this group are taken.
    1.75 @@ -52,9 +66,6 @@
    1.76  Other, but not covered, group members are: %FIXME:  are these all MTAs of that group? why these and not others?
    1.77  %TODO: what about `courier-mta'?
    1.78  
    1.79 -% http://www.yolinux.com/TUTORIALS/LinuxTutorialMailMTA.html
    1.80 -% http://homepages.tesco.net/~J.deBoynePollard/Reviews/UnixMTSes/
    1.81 -
    1.82  Here follows a small introduction to each of the five.
    1.83  
    1.84  \subsection{\sendmail}
    1.85 @@ -69,10 +80,11 @@
    1.86  \sendmail\ is focused on transfering mails between different protocols and networks, this lead to a very flexible (though complex) configuration.
    1.87  
    1.88  The latest version is 8.14.3 from May 2008.
    1.89 +The program is distributed under the \name{Sendmail License} as both, \freesw\ and proprietary software of \name{Sendmail, Inc.}.
    1.90 +
    1.91  Further development will go into the project \name{MeTA1} which succeeds \sendmail.
    1.92  
    1.93  More information can be found on the \sendmail\ homepage \citeweb{sendmail:homepage} and on \citeweb{wikipedia:sendmail} and \citeweb{jdebp}.
    1.94 -%FIXME: license
    1.95  
    1.96  
    1.97  \subsection{\name{qmail}}
    1.98 @@ -89,18 +101,48 @@
    1.99  
   1.100  
   1.101  \subsection{\name{postfix}}
   1.102 -%TODO: author, date of first release, basic intention of program, ...
   1.103 -%TODO: references to various descriptions
   1.104 +The \name{postfix} project was started in 1999 at \name{IBM research}, then called \name{VMailer} or \name{IBM Secure Mailer}.
   1.105 +Wietse Venema's program ``attempts to be fast, easy to administer, and secure. The outside has a definite Sendmail-ish flavor, but the inside is completely different.''\citeweb{postfix:homepage}
   1.106 +In fact, \name{postfix} was mainly designed after qmail's architecture to gain security.
   1.107 +But in contrast to \name{qmail} it aims much more on being fast and full-featured.
   1.108 +
   1.109 +Today \name{postfix} is taken by many \unix systems and \gnulinux distributions as default \MTA.
   1.110 +
   1.111 +The latest stable version is numbered 2.5.5 from August 2008.
   1.112 +\name{postfix} is covered by the \name{IBM Public License 1.0} which is a \freesw\ license.
   1.113 +
   1.114 +Additional information is available on the program's homepage \citeweb{postfix:homepage}, on \citeweb{jdebp} and \citeweb{wikipedia:postfix}.
   1.115 +
   1.116  
   1.117  \subsection{\name{exim}}
   1.118 -%TODO: author, date of first release, basic intention of program, ...
   1.119 -%TODO: references to various descriptions
   1.120 +\name{exim} was started in 1995 by Philip Hazel at the \name{University of Cambridge}.
   1.121 +Its age is about the same as \name{qmail}'s, but the architecture is totally different.
   1.122 +
   1.123 +While \name{qmail} took a completely new approach, \name{exim} forked of \name{smail-3}, and therefor is monolitic like that and like \sendmail.
   1.124 +But having no separation of the individual components of the system, like \name{qmail} and \name{postfix} have, did not hurt.
   1.125 +Its security is comparably good.
   1.126 +
   1.127 +\name{exim} is highly configurable, especially in the field of mail policies.
   1.128 +This makes it easy to specify how mail is routed through the system and who is allowed to send email to whom.
   1.129 +Also interfaces for integration of virus and spam check programs are provided by design.
   1.130 +
   1.131 +The program is \freesw, released under the \GPL. The latest stable version is 4.69 from December 2007.
   1.132 +
   1.133 +One finds \name{exim} on its homepage \citeweb{exim:homepage}. More information about it can be retrieved from \citeweb{wikipedia:exim} and \citeweb{jdebp}.
   1.134 +
   1.135  
   1.136  \subsection{\masqmail}
   1.137  The \masqmail\ program was written by Oliver Kurth, starting in 1999.
   1.138 -His aim was to create a \mta\ which is especially focused on computers with dial-up connections to the internet.
   1.139 -\masqmail\ handles situations which are rarely solveable with the common \MTA{}s.
   1.140 -%TODO: references to various descriptions
   1.141 +His aim was to create a small \mta\ which is especially focused on computers with dial-up connections to the internet.
   1.142 +\masqmail\ is easy configurable for situations which are rarely solveable with the common \MTA{}s.
   1.143  
   1.144 +\masqmail\ queues mail for destinations outside the local network if no connection to the internet is online.
   1.145 +If the machine goes online, this mail is sent.
   1.146 +Mail to local machines is sent immediately.
   1.147  
   1.148 -% briefly discuss the border between small MTAs (sendmail, masqmail) and state-of-the-art mailservers (postfix) and groupware (notes, exchange): give usecases.
   1.149 +While the other \MTA{}s are more general purpose \MTA{}s, \masqmail\ aims on special situations only.
   1.150 +Nevertheless can it handle ordinary mail transfers too.
   1.151 +
   1.152 +\masqmail\ is released under the \GPL, which makes it \freesw. The latest stable version is 0.2.21 from November 2005.
   1.153 +
   1.154 +The program's new homepage \citeweb{masqmail:homepage} provides further information about this \MTA.