Mercurial > docs > diploma

annotate thesis/tex/2-MailTransferAgents.tex @ 97:e3987669b64b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
this is no book of course ;-)
author meillo@marmaro.de
date Sun, 16 Nov 2008 15:33:10 +0100
parents a6f8a93abd64
children d24fdd3d5990
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
1 \chapter{Mail transfer agents}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
2
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
3 After having read about the history of electronic mail and the basics of \mta{}s in the last chapter, this chapter introduces a group of \mta{}s. Among them, the already mentioned \sendmail. The selected group will be delimited against other groups of \MTA{}s, which are described as well.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
4
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
5 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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
6
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
7
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
8 \section{Types of \MTA{}s}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
9 ``Mail transfer agent'' is a term covering a variety of programs. One thing is common to them: they transfer email from one \emph{thing} to another. These \emph{things} can be hosts, meaning independent machines, or protocols like \NAME{SMTP} and \NAME{UUCP}, between which mail is transfered.\footnote{\sendmail{}'s initial purpose was moving mail between \NAME{UUCP}, \NAME{SMTP}, and \name{Berknet}.}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
10
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
11 Beside this common property, \MTA{}s can be very different. Some of them have \NAME{POP3} and/or \NAME{IMAP} servers included. Some can fetch mails through these protocols. Others have have all features you can think of. And maybe there are some that do nothing else but transporting email.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
12
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
13 Following are groups of \mta{}s that will \emph{not} be regarded further.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
14
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
15 \subsection*{Relay-only \MTA{}s}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
16 \label{subsec:relay-only}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
17 This is the most simple kind of \MTA. It transfers 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 from outside the system, and they do not deliver locally.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
18
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
19 Most \MTA{}s can be configured to act as such a \name{forwarder}. But this is usually an additional functionality.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
20
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
21 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 a \name{relay-only} \MTA, while there is one \name{mail server} that acts as a \name{smart host}. The ``dumb'' clients send mail to this one \name{mail server} which does all the work.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
22
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
23 Examples for that group are: \name{nullmailer}, \name{ssmtp} and \name{esmtp}.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
24
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
25
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
26 \subsection*{Groupware}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
27 Normally the term ``groupware'' does not mean one single program, but a suite of programs. They build a framework which is then populated with various modules that provide actual funktionality. Modules for mail transfer, file storage, calendars, resource management, instant messaging, etc., are commonly available.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
28
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
29 One would use one of these program suites if the main work to do is not mail transfer, but providing integrated communication facilities 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 one may use \name{groupware} on the home server for his family members also.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
30
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
31 Examples are: \name{Lotus Notes}, \name{Microsoft Exchange}, \name{OpenGroupware.org} and \name{eGroupWare}.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
32
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
33
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
34 \subsection*{``Real'' \MTA{}s}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
35 There is a third type of \mta{}s in between the minimalistic \name{relay-only} \MTA{}s and the bloated \name{groupware}. Those programs may be named ``real \MTA{}s'', or ``proper \MTA{}s'', though there is no common name. They are what is meant with the term ``\mta''.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
36
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
37 Common to them is their focus on transfering email, while being able to act as \name{smart host}. Their variety ranges from ones mostly restricted to mail transfer (\name{qmail}) to others already having interfaces for adding further mail processing modules (\name{postfix})---thus everything in between the other two groups. %FIXME: are postfix and qmail good examples?
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
38
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
39 This group is of importance in this document. The programs selected for the comparison are ``real \MTA{}s''.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
40
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
41
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
42
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
43 \subsection*{Programs to sort out}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
44
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
45 \name{Mail transfer agent}s can be segmented in various ways, apart from the classification above. Groups of programs wiproperties significantly different from \masqmail\ will be sorted out now.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
46
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
47 \subsection*{Non-\emph{sendmail-compatible} \MTA{}s}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
48 Due to \sendmail's significance---described in section \ref{sec:sendmail}---compatiblity interfaces for \sendmail\ are of importance for \unix\ \MTA{}s. Being not \emph{sendmail-compatible} does not need to matter for some fields of action, but makes the program ineligible for serving as a general purpose \MTA\ on \unix\ systems.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
49
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
50 Hence all \MTA{}s not having a \emph{sendmail-compatible} interface or not offering it as a compatibility addon, will not be covered here.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
51
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
52 An Examples here is \name{Apache James}. %FIXME: check if correct
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
53
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
54
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
55 \subsection*{Non-free software}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
56 Only programs being \freesw\ are regarded, because comparing \freesw\ with proprietary or commercial software is not what typical users of programs like \masqmail\ do. Comparison with those non-free programs may be a point for large \freesw\ projects, trying to step into the business world. Small projects, mostly used by individuals at home, need to be compared against other projects of similar shape.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
57
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
58 The comparison should be seen from \masqmail's point of view, so non-free software is out of the way.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
59
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
60
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
61
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
62 \section{Popular \MTA{}s}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
63 The programs remaining are \emph{sendmail-compatible} ``smart'' \MTA{}s that focus on mail transfer and are \freesw. One would not use a program for a job it is not suited for. Therefor only \mta{}s that are mostly similar to \masqmail\ are regarded.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
64
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
65 For the comparision, five programs are taken. These are: \sendmail, \name{qmail}, \name{postfix}, \name{exim}, and \masqmail. The four alternatives to \masqmail\ are the most important representatives of the regarded group. % FIXME: add ref that affirm that
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
66
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
67 \name{courier-mta} is also a member of this group, being even closer to \name{groupware} than \name{postfix}. It is excluded here, because the \NAME{IMAP} and webmail parts of the mail server suite are more in focus than its \MTA. Common mail server setups even bundle \name{courier-imap} with \name{postfix}.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
68
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
69 Other members are: \name{smail}, \name{zmailer}, \name{mmdf}, and more; they all are less important and rarely used.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
70
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
71 Following is a small introduction to each of the five programs chosen for comparision.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
72
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
73 \subsection*{\sendmail}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
74 \label{sec:sendmail}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
75 \sendmail\ is the most popular \mta. Since it was one of the first \MTA{}s and was shipped by many vendors of \unix\ systems.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
76
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
77 The program was written by Eric Allman as the successor of his program \name{delivermail}. \sendmail\ was first released with \NAME{BSD} 4.1c in 1983. Allman was not the only one working on the program. Other people developed own versions of it and a variety of flavors came up, especially in the late eighties when Allman was inactive.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
78
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
79 \sendmail\ is focused on transfering mails between different protocols and networks, this lead to a very flexible (though complex) configuration.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
80
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
81 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.}.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
82
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
83 Further development will go into the project \name{MeTA1} which succeeds \sendmail.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
84
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
85 More information can be found on the \sendmail\ homepage \citeweb{sendmail:homepage} and on \citeweb{wikipedia:sendmail} and \citeweb{jdebp}.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
86
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
87
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
88 \subsection*{\name{qmail}}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
89 \label{sec:qmail}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
90 \name{qmail} is seen by its community as ``a modern SMTP server which makes sendmail obsolete''. It was written by Daniel~J.\ Bernstein starting in 1995. His primary goal was to create a secure \MTA\ to replace the popular, but vulnerable, \sendmail.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
91
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
92 \name{qmail} first introduced may innovative concepts in \mta\ design and is generally seen as the first security-aware \MTA\ developed.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
93
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
94 Since November 2007, \name{qmail} is released in the \name{public domain} which makes it \freesw. The latest release is 1.03 from July 1998.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
95
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
96 The programs homepages are \citeweb{qmail:homepage1} and \citeweb{qmail:homepage2}. Further information about \name{qmail} is available on \citeweb{lifewithqmail}, \citeweb{wikipedia:qmail} and \citeweb{jdebp}.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
97
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
98
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
99 \subsection*{\name{postfix}}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
100 \label{sec:postfix}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
101 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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
102
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
103 Today \name{postfix} is taken by many \unix systems and \gnulinux distributions as default \MTA.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
104
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
105 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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
106
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
107 Additional information is available on the program's homepage \citeweb{postfix:homepage}, on \citeweb{jdebp} and \citeweb{wikipedia:postfix}.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
108
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
109
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
110 \subsection*{\name{exim}}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
111 \label{sec:exim}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
112 \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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
113
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
114 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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
115
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
116 \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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
117
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
118 The program is \freesw, released under the \GPL. The latest stable version is 4.69 from December 2007.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
119
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
120 One finds \name{exim} on its homepage \citeweb{exim:homepage}. More information about it can be retrieved from \citeweb{wikipedia:exim} and \citeweb{jdebp}.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
121
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
122
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
123 \subsection*{\masqmail}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
124 \label{sec:masqmail}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
125 The \masqmail\ program was written by Oliver Kurth, starting in 1999. 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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
126
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
127 \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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
128
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
129 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.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
130
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
131 \masqmail\ is released under the \GPL, which makes it \freesw. The latest stable version is 0.2.21 from November 2005.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
132
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
133 The program's new homepage \citeweb{masqmail:homepage} provides further information about this \MTA.
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
134
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
135
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
136
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
137
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
138 \section{Comparison of \MTA{}s}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
139
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
140 % http://shearer.org/MTA_Comparison
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
141 % http://www.geocities.com/mailsoftware42/
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
142 % http://fanf.livejournal.com/50917.html
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
143 % http://archives.neohapsis.com/archives/postfix/2006-07/1762.html
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
144 % http://www.oreillynet.com/lpt/a/6849
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
145 % http://www.mailradar.com/mailstat/
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
146
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
147 \subsection{First release}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
148 sendmail: 1983
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
149
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
150 postfix: 1999
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
151
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
152 qmail: 1996 (first beta 0.70), 1997 (first general 1.0)
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
153
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
154 exim: 1995
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
155
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
156 masqmail: 1999
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
157
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
158 exchange: 1993
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
159
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
160
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
161 \subsection{Lines of code (with sloccount on debian packages)}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
162 sendmail: 93k
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
163
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
164 postfix: 92k
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
165
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
166 qmail: 18k
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
167
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
168 exim: 54k
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
169
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
170 masqmail: 14k
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
171
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
172 exchange: (no source available)
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
173
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
174
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
175 \subsection{Architecture}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
176 sendmail: monolitic
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
177
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
178 postfix: modular
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
179
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
180 qmail: modular
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
181
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
182 exim: monolitic
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
183
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
184 masqmail: monolitic
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
185
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
186 Like its anchestor \sendmail, \masqmail\ is a monolitic program. It consists of only one \emph{setuid root}\footnote{Runs as user root, no matter which user invoked it.}\index{setuid root} binary file, named \path{masqmail}. All functionality is included in it; of course some more comes from dynamic libraries linked.
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
187
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
188
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
189 exchange: (unknown)
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
190
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
191
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
192 \subsection{Design goals}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
193 sendmail: flexibility
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
194
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
195 postfix: performance and security
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
196
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
197 qmail: security
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
198
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
199 exim: general, flexible \& extensive facilities for checking
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
200
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
201 masqmail: for non-permanent internet connection
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
202
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
203 exchange: groupware
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
204
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
205
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
206 \subsection{Market share (by Bernstein in 2001)}
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
207 sendmail: 42\%
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
208
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
209 postfix: 1.6\%
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
210
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
211 qmail: 17\%
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
212
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
213 exim: 1.6\%
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
214
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
215 masqmail: (unknown)
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
216
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
217 exchange: 18\%
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
218
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
219
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
220
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
221
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
222 1) complexity
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
223
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
224 2) security
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
225
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
226 3) simplicity of configuration and administration
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
227
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
228 4) flexibility of configuration and administration
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
229
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
230 5) code size
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
231
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
232 6) code quality
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
233
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
234 7) documentation (amount and quality)
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
235
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
236 8) community (amount and quality)
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
237
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
238 9) used it myself
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
239
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
240 10) had problems with it
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
241
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
242
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
243
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
244
93
a6f8a93abd64 new chapter 4 (split ch5); added lots of annotations
meillo@marmaro.de
parents: 92
diff changeset
245 % quality criteria
a6f8a93abd64 new chapter 4 (split ch5); added lots of annotations
meillo@marmaro.de
parents: 92
diff changeset
246 % standards of any kind
a6f8a93abd64 new chapter 4 (split ch5); added lots of annotations
meillo@marmaro.de
parents: 92
diff changeset
247 % how to compare?
a6f8a93abd64 new chapter 4 (split ch5); added lots of annotations
meillo@marmaro.de
parents: 92
diff changeset
248 % (bewertungsmatrix) objectivity
a6f8a93abd64 new chapter 4 (split ch5); added lots of annotations
meillo@marmaro.de
parents: 92
diff changeset
249 % how many criterias for ``good''?
a6f8a93abd64 new chapter 4 (split ch5); added lots of annotations
meillo@marmaro.de
parents: 92
diff changeset
250
a6f8a93abd64 new chapter 4 (split ch5); added lots of annotations
meillo@marmaro.de
parents: 92
diff changeset
251
a6f8a93abd64 new chapter 4 (split ch5); added lots of annotations
meillo@marmaro.de
parents: 92
diff changeset
252
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
253
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
254
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
255 \subsubsection*{masqmail stuff}
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
256
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
257 The \masqmail\ executable can be called under various names for \name{sendmail-compatibility} reasons. This is commonly organized by creating symbolic links with with different names to the \masqmail\ executable. These are \path{/usr/lib/sendmail} and \path{/usr/sbin/sendmail} because many programs expect a \mta\ to be located there. Further more \sendmail\ provides shortcuts by calling it with a different name instead of supplying command line arguments. The best known of it is \path{mailq}, which is equivilent to calling the \MTA\ with the argument \verb+-bq+. \masqmail\ reacts to the names \path{mailq}, \path{smtpd}, \path{mailrm}, \path{runq}, \path{rmail}, and \path{in.smtpd}. The last four are an addition to \sendmail. Not implemented is the name \path{newaliases} because it is not relevant to \masqmail. To provide the command nonetheless, one may write a shell script located at \path{/usr/bin/newaliases}, that simply invokes \verb+masqmail -bi+.
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
258
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
259 %masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
260 %sendmail: hoststat, mailq, newaliases, purgestat, smtpd
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
261
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
262 \masqmail\ is written in the \NAME{C} programming language. The program, as of version 0.2.21, consists of 34 source code and eight header files, containing about 9,000 lines of code\footnote{Measured with \name{sloccount} by David A.\ Wheeler.}. Additionally, it includes a \name{base64} implementation (about 300 lines) and \name{md5} code (about 150 lines). For systems that do not provide \name{libident}, this library is distributed as well (circa 600 lines); an available shared library however has higher precedence in linking.
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
263
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
264 The only mandatory dependency is \name{glib}---a cross-platform software utility library, originated in the \NAME{GTK+} project. It provides safer replacements for many standard library functions. (The unsafe \verb+sprintf()+ is one example.) Also it offers handy data containers, easy-to-use implementations of data structures, and much more.
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
265
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
266 With \masqmail\ comes the small tool \path{mservdetect}; it helps setting up a configuration that uses the \name{mserver} system to detect the online state. Two other binaries get compiled for testing purposes: \path{readtest} and \path{smtpsend}. All three programms use \masqmail\ source code; they only add a file with a \verb+main()+ function each.
89
3b5ba7331eb5 complete restructuring of whole document
meillo@marmaro.de
parents:
diff changeset
267
92
e050221efd38 much restructuring again
meillo@marmaro.de
parents: 89
diff changeset
268 \masqmail\ does not provide an interface for modules with additional functionality. There exists no add-on or module system. But the code is separated by function to the various source files, and some functional parts can be included or excluded by defining symbols. This means adding some argument (like \verb+--enable-maildir+) to the \verb+configure+ call. Thus the concerning code gets not removed by the preprocessor.