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1 .RN 1
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2
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3 .H0 "Introduction
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4 .P
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5 This chapter introduces MH, its history, concepts and how it is used.
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6 It describes nmh's code base and community to give the reader
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7 a better understanding of the state from which mmh started off.
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8 Further more, this chapter outlines the mmh project itself,
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9 describing the motivation for it and its goals.
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10
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11
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12 .H1 "MH \(en the Mail Handler
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13 .P
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14 MH is a conceptual email system design and its concrete implementation.
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15 Notably, MH had started as a design proposal at RAND Corporation,
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16 where the first implementation followed later.
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17 In spirit, MH is similar to Unix, which
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18 influenced the world more in being a set of system design concepts
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19 than in being a specific software product.
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20 The ideas behind Unix are summarized in the \fIUnix philosophy\fP.
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21 MH follows this philosophy.
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22
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23 .U2 "History
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24 .P
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25 In 1977 at RAND Corporation, Norman Shapiro and Stockton Gaines
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26 had proposed the design
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27 of a new mail handling system, called ``Mail Handler'' (MH),
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28 to superseed RAND's old monolithic ``Mail System'' (MS).
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29 Two years later, in 1979, Bruce Borden took the proposal and implemented a
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30 prototype of MH.
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31 Before the prototype had been available, the concept was
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32 believed to be practically unusable.
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33 But the prototype had proven successful and replaced MS thereafter.
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34 In replacing MS, MH grew to an all-in-one mail system.
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35 .P
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36 In the early Eighties,
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37 the University of California at Irvine (UCI) had started to use MH.
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38 They also took over its development and pushed MH forward.
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39 Marshall T. Rose and John L. Romine became the driving force then.
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40 This was the time when the Internet appeared, when UCB implemented
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41 the TCP/IP stack, and when Allman wrote Sendmail.
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42 MH was extended as emailing became more featured.
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43 The development of MH was closely related to the development of email
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44 RFCs. In the advent of MIME, MH was the first implementation of this new
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45 email standard.
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46 .P
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47 In the Nineties, MH had been moved into the public domain, making it
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48 attractive to Free Software developers.
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49 The Internet had became popular and in December 1996,
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50 Richard Coleman initiated the ``New Mail Handler'' (nmh) project.
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51 The project is a fork of MH 6.8.3 and bases strongly on the
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52 \fILBL changes\fP by Van Jacobson, Mike Karels and Craig Leres.
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53 Colman intended to modernize MH and improve its portability and
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54 MIME handling capabilities.
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55 This should be done openly within the Internet community.
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56 The development of MH at UCI stopped after the 6.8.4 release in
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57 February 1996, soon after the development of nmh had started.
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58 Today, nmh almost completely replaced the original MH.
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59 Some systems might still provide old MH, but mainly for historical reasons.
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60 .P
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61 In the last years, the work on nmh was mostly maintenance work.
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62 However, the development revived in December 2011 and stayed busy since then.
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63
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64 .U2 "Concepts
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65 .P
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66 MH is a toolchest, modelled after the Unix toolchest. It consists of a
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67 set of tools, each covering a specific task of email handling, like
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68 composing a message, replying to a message, refiling a message to a
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69 different folder, listing the messages in a folder.
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70 All of the programs operate on a common mail storage.
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71 .P
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72 The mail storage consists of \fImail folders\fP (directories) and
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73 \fPmessages\fP (regular files).
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74 Each message is stored in a separate file in the format it had been
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75 received (i.e. transfer format).
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76 The files are named with ascending numbers in each folder.
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77 The specific format of the mail storage characterizes MH in the same way
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78 like the format of the file system characterizes Unix.
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79 .P
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80 MH tools maintain a \fIcontext\fP, which includes the current mail folder.
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81 Processes in Unix have a similar context, containing the current working
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82 directory, for instance. In contrast, the process context is maintained
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83 by the Unix kernel automatically, whereas MH tools need to maintain the MH
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84 context themselves.
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85 The user can have one MH context or multiple ones, he can even share it
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86 with other users.
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87 .P
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88 Messages are named by their numeric filename, but they can have symbolic names,
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89 too. These are either automatically updated
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90 position names like being the next or the last message,
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91 or user-settable group names for arbitrary sets of messages.
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92 These names are called sequences.
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93 Sequences can be bound to the containing folder or to the context.
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94 .P
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95 The user's \fIprofile\fP is a file that contains his MH configuration.
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96 Default switches for the individual tools can be specified to
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97 adjust them to the user's personal preferences.
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98 Multiple versions of the same command with different
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99 default values can also be created very easily.
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100 Form templates for new messages or for replies are easily changable,
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101 and output is adjustable with format files.
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102 Almost every part of the system can be adjusted to personal preference.
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103 .P
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104 The system is well scriptable and extendable.
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105 New MH tools are built out of or on top of existing ones quickly.
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106 Further more, MH encourages the user to taylor, extend and automate the system.
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107 As the MH toolchest was modelled after the Unix toolchest, the
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108 properties of the latter apply to the former as well.
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109
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110
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111 .U2 "Example Session
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112 .P
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113 Following is an example mail handling session with mmh.
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114 It should be mostly compatible with nmh and old MH.
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115 Details might vary but the look'n'feel is the same.
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116 .DS
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117 $ \f(CBinc\fP
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118 Incorporating new mail into inbox...
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119
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120 1+ 2012-05-16 11:16 meillo@dream.home Hello
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121 2 2012-05-16 11:17 meillo@dream.home book
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122
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123 $ \f(CBshow\fP
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124 Date: Wed, 16 May 2012 11:16:00 +0200
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125 To: meillo
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126 From: <meillo@dream.home.schnalke.org>
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127 Subject: Hello
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128
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129 part text/plain 13
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130 mmh is great
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131
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132 $ \f(CBnext\fP
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133 Date: Wed, 16 May 2012 11:17:24 +0200
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134 To: meillo
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135 From: <meillo@dream.home.schnalke.org>
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136 Subject: book
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137
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138 part text/plain 79
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139 Hello meillo,
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140
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141 have a look at the ``Daemon book''. You need to read that!
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142
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143 foo
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144
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145 $ \f(CBrmm 1\fP
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146
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147 $ \f(CBscan\fP
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148 2+ 2012-05-16 11:17 meillo@dream.home book
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149
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150 $
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151 .DE
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152
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153
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154 .H1 "nmh: Code and Community
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155 .P
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156 In order to understand the state, goals and dynamics of a project,
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157 one needs to know its history. MH predates the Internet,
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158 it comes from times before networking was universal,
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159 times when emailing was small, short and simple.
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160 Then it grew, spread and adopted to the changes email went through.
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161 The core-concepts, however, remained the same.
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162 During the 80s a small group of students at the University of
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163 California, actively worked on MH. They added features and optimized,
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164 like it is common for scientific work. This is still in pre-ANSI C
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165 times. The source code contains many ancient parts. Code constructs
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166 specific to BSD or hardware of that time are usual.
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167 .P
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168 Nmh started eight years after the ANSI C standard had been
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169 established. A more modern coding style entered the code base. Still
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170 a part of the developers come from ``the old days''. The developer
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171 base became more diverse and thus the code had different style.
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172 Programming practices
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173 from different decades merged into the project. Different coding
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174 styles came together. It appears as if multiple peers added code
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175 parts, resulting in a conclomeration rather than a homogenic
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176 of-one-cast mail system. Still, the basic concepts hold it together.
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177 They were mostly untouched throughout the years.
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178 .P
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179 Although, at the surface, nmh is a toolchest, meaning a collection
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180 of completely modularized small programs, on the source code level,
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181 it is much more interweaved. Parts of the basic functions are
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182 collected in a MH standard library, which is good, but often
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183 separate functions are compiled into programs, for effiency reasons.
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184 This lead to intricate innards.
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185 The advent of MIME rose the complexity of email by a magnitude. This
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186 is visible in nmh. The MIME-related parts are the most complex ones.
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187 It's also visible that MIME support had been added on top of the
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188 old MH later. The MH style made this easily possible, but it
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189 also lead to duplicated functions (e.g. \fLshow\fP, \fLmhshow\fP)
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190 and had not been thoroughly included into the concepts (e.g. the
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191 user-visible access to whole messages and MIME parts are inherently
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192 different).
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193 .P
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194 For backward-compatibility's sake, it is a common understanding to have the
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195 default settings to be compatible, requiring any new feature to be
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196 explicitely enabled.
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197 In consequence, the user needs to activate modern features explicitely
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198 to be able to use them.
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199 This puts a burden on new users, because nmh
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200 out-of-the-box keeps staying in the same ancient style, where users
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201 usually want to have it practical for modern emailing.
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202 But of course, this depends if nmh is seen to be a front-end or a
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203 back-end.
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204
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205
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206 .H1 "mmh
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207 .P
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208 I started to work on my experimental version in Fall 2011.
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209 In December, when I announced my work on the nmh-workers mailing list,
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210 .[
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211 nmh-workers mmh announce december
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212 .]
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213 the activity in nmh rose heavily.
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214 Suddently the community started to move.
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215 This movement was pushed much by Paul Vixie's ``edginess'' message.
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216 .[
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217 nmh-workers vixie edginess
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218 .]
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219 After long years of much stagnation, nmh became actively developed again.
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220 Hence, while I was working on mmh, the community was working on nmh,
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221 in parallel.
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222 .P
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223 The name \fImmh\fP stands for \fImeillo's mail handler\fP,
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224 because mmh is my own version of MH.
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225 (My login name is \fImeillo\fP.)
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226 The project follows my personal considerations and preferences.
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227 By calling it a personal project, I don't need to justify my decisions,
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228 though, still I do.
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229 This enabled me to follow my vision staightly and thus produce
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230 a result of greater pureness.
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231 This project model was inspired by the window manager \fIdwm\fP,
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232 which is Anselm Garbe's personal window manager \(en
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233 targeted to satisfy Garbe's personal needs whenever conflicts appear.
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234 dwm had remained much more focused on its original goals,
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235 whereas its community-driven predecessor \fIwmii\fP had
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236 grown large and lost it's leanness.
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237 This should not happen to mmh.
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238 .P
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239 Mmh can also stand for \fImodern mail handler\fP, and this is
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240 the variant chosen as titel for this document. One main focus of the
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241 project was to modernize nmh. Another main goal is resembled in the
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242 name \fIminimized mail handler\fP: Drop any parts that don't add
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243 to the main task of mmh, being a MUA.
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244 .P
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245 It should also be noted that \fLstrcmp("mmh","nmh")<0\fP is true.
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246 Although mmh bases on nmh, it is likely seen as a step backward.
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247 I agree.
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248 However, this step backward actually is a step forward,
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249 although in another direction.
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250
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251
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252 .H1 "This Thesis
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253
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254 .U2 "Motivation
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255 .P
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256 MH is the most important of very few command line toolchest email systems.
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257 (There's also \fIim\fP by Tatsuya Kinoshita,
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258 which operates on an MH mail storage.)
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259 Toolchests are powerful because they can be perfectly automated and
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260 extended. Toolchests are good back-ends for various sorts of front-ends.
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261 They allow multiple front-ends for different special needs
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262 to be implemented quickly and withough internal knowledge on emailing.
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263 Further more, toolchests are much better to maintain than large monolithic
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264 programs.
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265 As there are few toolchests for emailing and MH-like ones are the most
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266 popular amoung them, they should be developed further to keep their
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267 conceptional elegance and unique scripting qualities available to users.
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268 mmh will create a modern and convenient entry point for new, interested
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269 users to MH-like systems.
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270 .P
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271 The mmh project is motivated by deficites of nmh and
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272 my wish for general changes, combined
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273 with the nmh community's reluctancy to change.
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274 .P
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275 nmh hadn't adjusted to modern emailing needs well enough.
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276 The default setup was completely unusable for modern emailing.
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277 Too much setup work was required.
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278 Several modern features were already available but the community
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279 didn't wanted to have them as default.
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280 mmh is a way to change this.
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281 .P
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282 In my eyes, MH's concepts could be exploited even better and
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283 the style of the tools could be improved. Both would simplify
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284 and generalize the system, providing cleaner interfaces and more
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285 software leverage, at the same time.
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286 mmh is a way to demonstrate this.
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287 .P
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288 In providing several parts of an email system, nmh can hardly
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289 compete with the large specialized projects that focus
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290 on only one of the components.
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291 The situation can be improved by concentrating the development power
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292 on the most unique part of MH and letting the user pick his prefered
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293 set of other mail components.
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294 Today's pre-packaged software components encourage this model.
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295 mmh is a way to go for this approach.
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296 .P
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297 It's worthwhile to fork nmh for the development of mmh, because
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298 the two projects focus on different goals and differ in fundamental questions.
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299 The nmh community's reluctance to change conflicts
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300 with my strong will to change.
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301 In developing a separate experimental version new approaches can
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302 easily be tried out without the need to discuss changes beforehand.
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303 In fact, revolutionary changes are hardly possible otherwise.
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304 These reasons support the decision to start mmh as a fork of nmh.
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305 .P
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306 The mmh project provides the basis to implemented and demonstrated
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307 the listed ideas without the need to change nmh or its community.
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308 Of course, the results of the mmh project shall improve nmh, in the end.
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309
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310 .U2 "Target Field
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311 .P
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312 Any effort needs to be targeted towards a specific goal
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313 in order to be successful.
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314 Following is a description of the imagined typical mmh user.
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315 mmh should satisfy his needs.
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316 Actually, as mmh is my personal version of MH, this is a description
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317 of myself.
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318 .P
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319 The target user of mmh likes Unix and its philosophy.
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320 He likes to use programs that are conceptionally appealing.
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321 He's familiar with the command line and enjoys its power.
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322 He is at least capable of shell scripting and wants to improve his
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323 productivity by scripting the mail system.
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324 He naturally uses modern email features, like attachments,
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325 non-ASCII text, and digital cryptrography.
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326 He is able to setup email system components besides mmh,
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327 and actually likes the choice to pick the ones he preferes.
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328 He has a reasonably modern system that complies to standards,
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329 like POSIX and ANSI C.
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330 .P
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331 The typical user invokes mmh commands directly in an interactive
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332 shell session, but as well, he uses them to automate mail handling tasks.
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333 Likely, he runs his mail setup on a server machine, to which he connects
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334 via ssh. He might also have local mmh installations on his workstations,
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335 but does rather not rely on graphical frontends. He definitely wants
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336 to be flexible and thus be able to change his setup to suite his needs.
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337 .P
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338 The typical mmh user is a programmer himself.
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339 He likes to, occasionally, take the opportunity of Free Software to put
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340 hands on and get involved in the software he uses.
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341 Hence, he likes small and clean code bases and he cares for code quality.
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342 In general, he believes that:
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343 .BU
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344 Elegance \(en i.e. simplicity, clarity and generality \(en
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345 is most important.
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346 .BU
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347 Concepts are more important than the concrete implementation.
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348 .BU
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349 Code optimizations for anything but readability should be avoided
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350 if possible.
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351 .BU
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352 Having a lot of choice is bad.
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353 .BU
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354 Removed code is debugged code.
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355
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356 .U2 "Goals
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357 .P
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358 The general goals for the mmh project are the following:
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359 .IP "Stream-lining
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360 Mmh should be stripped down to its core, which is the MUA part of emailing.
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361 The feature set should be distilled to the ones really needed,
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362 effectively removing corner-cases.
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363 Functions that are not related to the main task should be removed.
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364 This includes, the MTA and MRA facilities.
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365 Choice should be reduced to the main options.
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366 .IP "Modernizing
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367 Mmh's feature set needs to become more modern.
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368 Better support for attachment and digital cryptography needs to be added.
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369 MIME support needs to be integrated deeper and more naturally.
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370 The modern email features need to be readily available, out-of-the-box.
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371 And on the other hand,
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372 bulletin board support and similar obsolete facilities need to be dropped
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373 out.
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374 Likewise, ancient technologies, like hardcopy terminals, should not
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375 be supported any further.
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376 .IP "Code style
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377 Mmh's source code needs to be updated to modern standards.
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378 Standardized library functions should replace non-standard versions
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379 whenever possible.
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380 Code should be separated into distinct modules when possible.
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381 Time and space optimizations should to be replaced by
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382 clear and readable code.
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383 A uniform programming style should prevail.
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384 .IP "Homogenity
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385 The available concepts need to be expanded as far as possible.
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386 A small set of concepts should prevail thoroughly throughout the system.
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387 The whole system should appear to be of-one-style.
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388 It should feel like being cast as one.
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