# HG changeset patch # User meillo@marmaro.de # Date 1224432001 -7200 # Node ID 997870769e5495bb62ed4835e47f3ddb3c7e2d0f # Parent fbf5165a390f807c5ce65084e29b7e310bb2c248 wrote about postfix, exim, masqmail; rewrote section about types of MTAs (unfinished) diff -r fbf5165a390f -r 997870769e54 thesis/tex/1-Candidates.tex --- a/thesis/tex/1-Candidates.tex Sun Oct 19 17:58:41 2008 +0200 +++ b/thesis/tex/1-Candidates.tex Sun Oct 19 18:00:01 2008 +0200 @@ -1,8 +1,10 @@ \chapter{\unix\ \MTA{}s} This chapter introduces a group of \mta{}s. -These will be presented to the reader in a short overview and with the most important facts. -The next chapter will show a comparison of the candidates in several disciplines. +The selected group will be delimited against other groups of \MTA{}s, which are described as well. + +The chosen programs will be presented to the reader in a short overview and with the most important facts. +The next chapter will show a comparison of these programs in several disciplines. \section{Types of \MTA{}s} @@ -16,32 +18,44 @@ Others have have every feature you can think of. And maybe there are some that do nothing else, but transporting email. +Here are groups of \mta{}s that will not be regarded in the following chapter. +% Prof: briefly discuss the border between small MTAs (sendmail, masqmail) and state-of-the-art mailservers (postfix) and groupware (notes, exchange): give usecases. -\section{The ones not regarded here} -The candidates for the competition in the next chapter are a subset of the \MTA{}s available. -Comparision between totally different programs (apart of one function) makes not much sense. -One would not use a program for a job it is not suited for. -Therefor \mta{}s that are rarely similar to \masqmail\ are not regarded. +\subsection{Relay-only \MTA{}s} +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. -The first group of programs to sort out are the so called \name{groupware} programs. -These provide a whole lot of functions, including mail transfer, file storage, calendars, resource management, instant messaging and more. +Most \MTA{}s can be configured to act as such a forwarder. But this is usually an additional functionality. + +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''. + +Examples for that group are: \name{nullmailer}, \name{ssmtp} and \name{esmtp}. + + +\subsection{Groupware} +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. + +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. + Examples for this kind of programs are: \name{Lotus Notes}, \name{Microsoft Exchange}, \name{OpenGroupware.org} and \name{eGroupWare}. -The second group are the \name{relay-only} \MTA{}s. -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}. -Most \MTA{}s can be configured to act as such a forwarder. -But this is normally an additional functionality. -Examples for that group are: \name{nullmailer}, \name{ssmtp} and \name{esmtp}. +\subsection{More limitations} Third, only \emph{sendmail-compatible} \MTA{}s will be regarded in the competition. -Hence all \MTA{}s not having a \emph{sendmail-compatible} interface or not offering it as a compatibility addon, will not be covered here. +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 The reason is the heavy reliance of \unix\ systems on the existance of a programs called \path{sendmail}. This has historical reasons. See section \ref{sec:sendmail} for further information. Further more, only programs with source code available are regarded. %FIXME: why -\section{The competitors} +\subsection{The ones not regarded here} +The candidates for the competition in the next chapter are a subset of the \MTA{}s available. +Comparision between totally different programs (apart of one function) makes not much sense. %FIXME: better words +One would not use a program for a job it is not suited for. +Therefor \mta{}s that are rarely similar to \masqmail\ are not regarded. + + +\section{The programs regarded} The programs remaining are \emph{sendmail-compatible} ``smart'' \MTA{}s that do not offer masses of features unrelated to mail transport. For the comparision, five programs of this group are taken. @@ -52,9 +66,6 @@ Other, but not covered, group members are: %FIXME: are these all MTAs of that group? why these and not others? %TODO: what about `courier-mta'? -% http://www.yolinux.com/TUTORIALS/LinuxTutorialMailMTA.html -% http://homepages.tesco.net/~J.deBoynePollard/Reviews/UnixMTSes/ - Here follows a small introduction to each of the five. \subsection{\sendmail} @@ -69,10 +80,11 @@ \sendmail\ is focused on transfering mails between different protocols and networks, this lead to a very flexible (though complex) configuration. The latest version is 8.14.3 from May 2008. +The program is distributed under the \name{Sendmail License} as both, \freesw\ and proprietary software of \name{Sendmail, Inc.}. + Further development will go into the project \name{MeTA1} which succeeds \sendmail. More information can be found on the \sendmail\ homepage \citeweb{sendmail:homepage} and on \citeweb{wikipedia:sendmail} and \citeweb{jdebp}. -%FIXME: license \subsection{\name{qmail}} @@ -89,18 +101,48 @@ \subsection{\name{postfix}} -%TODO: author, date of first release, basic intention of program, ... -%TODO: references to various descriptions +The \name{postfix} project was started in 1999 at \name{IBM research}, then called \name{VMailer} or \name{IBM Secure Mailer}. +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} +In fact, \name{postfix} was mainly designed after qmail's architecture to gain security. +But in contrast to \name{qmail} it aims much more on being fast and full-featured. + +Today \name{postfix} is taken by many \unix systems and \gnulinux distributions as default \MTA. + +The latest stable version is numbered 2.5.5 from August 2008. +\name{postfix} is covered by the \name{IBM Public License 1.0} which is a \freesw\ license. + +Additional information is available on the program's homepage \citeweb{postfix:homepage}, on \citeweb{jdebp} and \citeweb{wikipedia:postfix}. + \subsection{\name{exim}} -%TODO: author, date of first release, basic intention of program, ... -%TODO: references to various descriptions +\name{exim} was started in 1995 by Philip Hazel at the \name{University of Cambridge}. +Its age is about the same as \name{qmail}'s, but the architecture is totally different. + +While \name{qmail} took a completely new approach, \name{exim} forked of \name{smail-3}, and therefor is monolitic like that and like \sendmail. +But having no separation of the individual components of the system, like \name{qmail} and \name{postfix} have, did not hurt. +Its security is comparably good. + +\name{exim} is highly configurable, especially in the field of mail policies. +This makes it easy to specify how mail is routed through the system and who is allowed to send email to whom. +Also interfaces for integration of virus and spam check programs are provided by design. + +The program is \freesw, released under the \GPL. The latest stable version is 4.69 from December 2007. + +One finds \name{exim} on its homepage \citeweb{exim:homepage}. More information about it can be retrieved from \citeweb{wikipedia:exim} and \citeweb{jdebp}. + \subsection{\masqmail} The \masqmail\ program was written by Oliver Kurth, starting in 1999. -His aim was to create a \mta\ which is especially focused on computers with dial-up connections to the internet. -\masqmail\ handles situations which are rarely solveable with the common \MTA{}s. -%TODO: references to various descriptions +His aim was to create a small \mta\ which is especially focused on computers with dial-up connections to the internet. +\masqmail\ is easy configurable for situations which are rarely solveable with the common \MTA{}s. +\masqmail\ queues mail for destinations outside the local network if no connection to the internet is online. +If the machine goes online, this mail is sent. +Mail to local machines is sent immediately. -% briefly discuss the border between small MTAs (sendmail, masqmail) and state-of-the-art mailservers (postfix) and groupware (notes, exchange): give usecases. +While the other \MTA{}s are more general purpose \MTA{}s, \masqmail\ aims on special situations only. +Nevertheless can it handle ordinary mail transfers too. + +\masqmail\ is released under the \GPL, which makes it \freesw. The latest stable version is 0.2.21 from November 2005. + +The program's new homepage \citeweb{masqmail:homepage} provides further information about this \MTA.