1 \chapter{\masqmail's present and future}

2

3 \section{Existing features}

4 This overview regards \masqmail\ version 0.2.21, the state this document starts off.

5

6 \masqmail\ is an \MTA, therefor it accepts mail on the command line and via \SMTP. Mail queueing and alias expansion is supported. \masqmail\ is able to deliver mail to local mailboxes (in \name{mbox} or \name{maildir} format) or pass it to a \name{mail delivery agent} (like \name{procmail}). Mail destinated to remote locations is sent via \SMTP. Outgoing \SMTP\ connections feature \name{SMTP-Auth} and \name{SMTP-after-POP} authentication, but incoming \SMTP\ does not.

7

8 As \masqmail\ is focused on non-permanent Internet connections, online state can be queried by three methods: reading from a file, reading the output of a command, or by asking an \name{mserver}. Each method may return a string indicating one of the available routes being online, or returning nothing to indicate offline state.

9

10 Delivery to recipients on the local host or in local nets is done at once; delivery to recipients on the Internet is only done when being online, and queued otherwise. Each online route may have a different mail server to which mail is relayed. Return address headers are modified appropriate if wished.

11

12 Additional to the \mta\ job, \masqmail\ also offers mail retrieval services with being a \NAME{POP3} client. Thus it can fetch mail from remote locations, dependent on the active online route.

13

14

15

16 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+.

17

18 %masqmail: mailq, mailrm, runq, rmail, smtpd/in.smtpd

19 %sendmail: hoststat, mailq, newaliases, purgestat, smtpd

20

21 \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.

22

23 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.

24

25 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.

26

27 \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.

28

29

30

31

32

33 \section{Discussion/Ideas}

34

35

36 << plans to get masqmail more popular again (if that is the goal) >> %FIXME

37

38

39 \subsection{Architecture}

40

41 << architecture diagram >>

42

43 (ssl) -> msg-in (local or remote protocol handlers) -> spam-filter (and more) -> queue -> msg-out (local-delivery by MDA, or remote-protocol-handlers) -> (ssl)

44

45 A design from scratch?

46

47 << what would be needed (effort) >> %FIXME

48

49 << would one create it at all? >> %FIXME

50

51 << should it be done? >> %FIXME

52

53

54

55 \subsection{local mail delivery}

56 But for example delivery of mail to local users is \emph{not} what \mta{}s should care about, although most \MTA\ are able to deliver mail, and many do. (\name{mail delivery agents}, like \name{procmail} and \name{maildrop}, are the right programs for this job.)

57

58

59

60 \subsection{various protocols}

61 protocols like \NAME{SMTP} and \NAME{UUCP}, between which mail is transferred.\footnote{\sendmail{}'s initial purpose was moving mail between \NAME{UUCP}, \NAME{SMTP}, and \name{Berknet}.}

62

63

64

65

66

67

68 http://fanf.livejournal.com/50917.html %how not to design an mta - the sendmail command

69 http://fanf.livejournal.com/51349.html %how not to design an mta - partitioning for security

70 http://fanf.livejournal.com/61132.html %how not to design an mta - local delivery

71 http://fanf.livejournal.com/64941.html %how not to design an mta - spool file format

72 http://fanf.livejournal.com/65203.html %how not to design an mta - spool file logistics

73 http://fanf.livejournal.com/65911.html %how not to design an mta - more about log-structured MTA queues

74 http://fanf.livejournal.com/67297.html %how not to design an mta - more log-structured MTA queues

75 http://fanf.livejournal.com/70432.html %how not to design an mta - address verification

76 http://fanf.livejournal.com/72258.html %how not to design an mta - content scanning

77

78

79

80 << concrete decisions based on results of the last 2 chapters >> %FIXME

81

82

83

84

85

86

87 \section{Directions to go}

88

89 \subsection{\masqmail\ in five years}

90 \label{sec:masqmail-in-5-years}

91 Now how could \masqmail\ be like in, say, five years?

92

93 << requirements >> %FIXME

94

95 << which parts to do >> %FIXME

96

97 << how to make masqmail future-safe >> %FIXME

98

99 << how to advertise masqmail >> %FIXME

100

101 << difference for free software >> %FIXME

102

103 << why is it worth to revive masqmail? >> %FIXME

104

105

106

107

108

109

110 \section{Work to do}

111

112 << which parts to take out and do within the thesis >> %FIXME

113

114