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1 .H0 "Introduction
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2 .P
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3 This chapter describes the background of the topics in this thesis.
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4 General knowledge of electronic mail is assumed.
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5 It explains the situation at the start of the project.
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6 It tries to describe from what state the project lifted of and where
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7 it headed to. This shall give an overview.
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8
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9
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10 .H1 "What is MH?
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11 .P
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12 MH is an electronic mail system, originating in the RAND Corporation.
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13 Historically, it had been a all-in-one mail system, with Mail Transfer
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14 Agent (MTA) and Mail User Agent (MUA).
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15 Later, when electronic mail systems changed, Mail Submission Agent (MSA)
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16 and Mail Retrieval Agent (MRA) facilities were added.
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17 The MTA became less important, whereas the MUA became even more the
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18 central part.
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19 .P
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20 First of all, MH is a style of a mail handling system.
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21 It had started as a design proposal, not as an implementation, and
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22 had in spirit remained so. This is similar to Unix, which much less
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23 is a specific software product, as it is a style of system design.
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24
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25 .H2 "History" no
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26 .P
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27 MH is an electronic mail system, originating in the RAND Corporation.
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28 In 1977, Norman Shapiro and Stockton Gaines had proposed the design
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29 of a new mail handling system, called ``Mail Handler'' (MH) for RAND,
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30 to superseed their ``Mail System'' (MS).
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31 Two years later, in 1979, XXX took the proposal and implemented a
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32 prototype of MH. It proved successful and replaced MS thereafter.
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33 .P
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34 A decade later, the University of California had started to use MH.
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35 They also took over its development and pushed MH forward.
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36 This had been the time when the Internet appeared, Berkeley implemented
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37 the TCP stack, and Sendmail was born. MH had often contained the first
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38 implementation of new RFCs.
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39 .P
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40 In the nineties, MH had been moved into the public domain, making it
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41 attractive to Free Software developers. The Internet had started to become
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42 mainstream and in 1997, Richard Coleman initiated the ``New Mail Handler''
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43 (nmh), a fork of MH. He intended to modernize MH, improve its MIME
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44 capabilities, and this should be done openly within the Internet
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45 community. Today, nmh almost completely replaced the original MH.
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46 .P
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47 Three versions of MH are available:
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48 .BU
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49 .B "Old MH" .
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50 In most cases it has been replaced by nmh, but some systems still
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51 provide old MH. As nmh is old MH-compatible, there exist few reasons
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52 not to upgrade to new.
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53 The development of old MH stopped almost completely.
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54 .BU
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55 .B Nmh .
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56 The most widespread version of MH. Backward-compatible to old MH.
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57 Provides new featues, which need to be activated explicitely.
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58 Its development went slowly in the previous years, but had revived
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59 in Fall 2011.
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60 .BU
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61 .B Mmh
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62 A descendent of nmh. Had started as a non-compatible experimental
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63 version, but became de facto a fork. Tries to expand the same
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64 principle concepts in a more modern way. This version of MH is the
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65 subject of this thesis.
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66
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67 .H2 "Concepts" no
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68 .P
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69 MH is a toolchest, modelled after the Unix toolchest. It consists of a
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70 bunch of tools, each covering one task of email handling. These programs
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71 operate on a common mail storage. The specific format of the mail storage
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72 also defines MH, like the file system structure defines Unix. It
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73 consists of directories (mail folders) and files (mail messages).
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74 Each file contains exactly one message in the format it had been
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75 received (i.e. transfer format). MH tools carry a state (context),
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76 consisting of current mail folder and current message. Messages can
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77 have symbolic names, like the next or last message or for some
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78 arbitrary group of messages. These names are called sequences.
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79 .P
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80 New MH tools can be build out of existing ones easily. Default values to
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81 commands are stored on a command name-basis, making it trivial to have
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82 different versions of the same command with different defaults. Most
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83 of the configuration is stored in the user's profile. Form templates,
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84 e.g. for new messages or replies, are exchangeable and output is generally
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85 adjustable with format files.
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86 .P
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87 MH allows the user to automate almost everything and to modify amost
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88 any behavior. The system is scriptable and extendable.
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89
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90
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91 .H1 "Understanding of the Code and Community
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92 .P
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93 In order to understand the state, goals and dynamics of a project,
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94 one needs to know its history. MH comes from a time before the
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95 Internet, a time before networking became universal, a time when
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96 emailing was small, short and simple. Then it grew, spread and
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97 adopted to the changes. The core-concepts, however, remained the
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98 same. During the XXX a small group of students at the University of
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99 California, actively worked on MH. They added features and optimized,
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100 like it is common for scientific work. This is still in pre-ANSI C
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101 times. The source code contains many ancient parts. Code constructs
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102 specific to BSD or hardware of that time are usual.
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103 .P
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104 Nmh started eight years after the ANSI C standard had been
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105 established. A more modern coding style entered the code base. Still
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106 a part of the developers come from ``the old days''. The developer
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107 base became more diverse and thus the code. Programming practices
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108 from different decades merged into the project. Different coding
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109 styles came together. It appears as if multiple peers added code
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110 parts, resulting in a conclomeration rather than an homogenic
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111 of-one-cast mail system. Still, the basic concepts hold it together.
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112 They were mostly untouched throughout the years.
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113 .P
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114 Although, at the surface, nmh is a toolchest, meaning a collection
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115 of completely modularized small programs, on the source code level,
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116 it is much more interweaved. Parts of the basic functions are
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117 collected in a MH standard library, which is good, but often
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118 separate functions are compiled into programs, for effiency reasons.
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119 This lead to intricate innards.
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120 The advent of MIME rose the complexity of email by a magnitude. This
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121 is visible in nmh. The MIME-related parts are the most complex ones.
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122 It's also visible that MIME support had been added on top of the
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123 original MH later. The MH style made this easily possible, but it
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124 also lead to duplicated functions (e.g. \fLshow\fP, \fLmhshow\fP)
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125 and had not been thoroughly included into the concepts (e.g. the
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126 user-visible access to whole messages and MIME parts are inherently
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127 different).
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128 .P
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129 For compatibility's sake, it is a common understanding to have the
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130 default settings to be compatible, requiring any new feature to be
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131 explicitely enabled. This puts a burden on new users, because nmh
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132 out-of-the-box keeps staying in the same ancient style, where users
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133 usually want to have it practical for modern emailing.
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134 But of course, this depends on if nmh is seen to be a front-end or a
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135 back-end.
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136
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137
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138 .H1 "My Vision
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139 .P
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140 The general goals of the mmh project are the following:
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141 .BU
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142 I believe that mmh should be perfectly suited for modern emailing,
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143 out-of-the-box.
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144 .BU
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145 I care less about compatibility and more about conceptionally elegant
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146 approaches.
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147 .BU
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148 I care for general, clear, and simple concepts.
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149 .BU
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150 I like to create an of-one-style email system. It should feel like
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151 cast as one.
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152 .BU
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153 I plan to remove any optimizations that rises obscurity, unless it
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154 appears to be neccessary to make mmh usable at all.
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155 .P
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156 .B "The target user in mind
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157 likes Unix and its philosophy.
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158 He likes to use programs that are conceptionally appealing.
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159 He's familiar with the command line and enjoys its power.
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160 He is at least capable of shell scripting and wants to improve his
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161 productivity by scripting the mail system.
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162 His computer and operating system are from post-ANSI C times.
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163 He likes to attach files, exchanges text containing non-ASCII
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164 characters, signs or encrypts his messages.
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165 He does not use bulletin boards anymore, nor non-mbox style mail
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166 drops, nor does he rely on compatibility to nmh.
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167 He already has and MTA/MSA and MRA running or is able to set them
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168 up.
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169 He does not want to have to read a book in order to make his MUA
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170 usable.
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171
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172
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173 .H1 "Things to do
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174 .BU
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175 Remove any MTA and MRA facilities. Mmh shall concentrate on the MUA
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176 task. Mail shall enter mmh's mail storage via the system mail drop
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177 and it shall leave mmh via the local \fLsendmail\fP command.
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178 .BU
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179 Remove any further functions that are not related to mmh's main task.
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180 Bulletin board support is on example. Also remove support for ancient
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181 technologies, like hardcopy terminals.
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182 .BU
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183 Refactor the source code to meet modern style criteria. Use
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184 standardized library functions when possible.
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185 .BU
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186 Replace performance optimizations by clear and readable code.
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187 .BU
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188 Reduce the feature set to the commonly used one, removing
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189 corner-cases. Set sane default values.
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190 .BU
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191 Add better attachment support. Add support for digital signatures and
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192 encryption.
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193 .BU
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194 Merge \fLshow\fP and \fLmhshow\fP into one single mail display program.
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195 Integrate MIME support deeper and more natural into MH.
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196 .BU
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197 Provide a ready-to-use setup out-of-the-box.
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