meillo@39: .RN 1
meillo@39: 
meillo@0: .H0 "Introduction
meillo@0: .P
meillo@32: This chapter introduces MH, its history, concepts and how it is used.
meillo@32: Then, it describes nmh's code base and community to give the reader
meillo@32: a better understanding of the state from which mmh started off.
meillo@32: Further more, this chapter lists the motivation and goals of the mmh project.
meillo@32: This chapter introduces MH, nmh and mmh to the reader and outlines
meillo@32: the mmh project itself.
meillo@8: 
meillo@0: 
meillo@28: .H1 "MH \(en the Mail Handler
meillo@0: .P
meillo@2: MH is an electronic mail system, originating in the RAND Corporation.
meillo@32: Most important for this thesis is that MH defines a mail handling concept.
meillo@32: In fact, MH had started as a design proposal, not as an implementation,
meillo@32: and in spirit it had remained this way. This is similar to Unix, which
meillo@32: influenced the world rather in being a set of system design concepts
meillo@32: than in being a specific software product.
meillo@27: .P
meillo@27: XXX Link to the Unix phil.
meillo@27: .P
meillo@27: XXX comparision to monolithic mail systems.
meillo@27: .P
meillo@27: XXX Differenciation of MUA and mail system.
meillo@2: 
meillo@11: .U2 "History
meillo@2: .P
meillo@2: MH is an electronic mail system, originating in the RAND Corporation.
meillo@32: In 1977 at RAND Corporation, Norman Shapiro and Stockton Gaines
meillo@32: had proposed the design
meillo@32: of a new mail handling system, called ``Mail Handler'' (MH),
meillo@32: to superseed RAND's old monolithic ``Mail System'' (MS).
meillo@27: Two years later, in 1979, Bruce Borden took the proposal and implemented a
meillo@32: prototype of MH.
meillo@32: Before the prototype had been available, the concept was
meillo@32: believed to be practically unusable because of being too slow.
meillo@32: But the prototype proved successful and replaced MS thereafter.
meillo@32: In replacing MS, MH became an all-in-one mail system.
meillo@2: .P
meillo@32: A decade later, the University of California at Irvine had started to use MH.
meillo@2: They also took over its development and pushed MH forward.
meillo@32: This was the time when the Internet appeared, UCB implemented
meillo@32: the TCP/IP stack, and Allman wrote Sendmail.
meillo@32: MH was extended as emailing got more features.
meillo@32: The development of MH was closely related to the development of email
meillo@32: RFCs. In the advent of MIME, MH was the first implementation of this new
meillo@32: email standard.
meillo@2: .P
meillo@2: In the nineties, MH had been moved into the public domain, making it
meillo@32: attractive to Free Software developers.
meillo@32: The Internet had started to become popular and in 1997,
meillo@32: Richard Coleman initiated the ``New Mail Handler'' (nmh) project,
meillo@32: a fork of MH, based on the \fILBL changes\fP by Van Jacobson, Mike Karels
meillo@32: and Craig Leres.
meillo@32: Colman intended to modernize MH and improve its portability and
meillo@32: MIME handling capabilities.
meillo@32: This should be done openly within the Internet community.
meillo@32: The development of MH stopped soon after the development of nmh had started.
meillo@32: Today, nmh almost completely replaced the original MH.
meillo@0: 
meillo@11: .U2 "Concepts
meillo@0: .P
meillo@8: MH is a toolchest, modelled after the Unix toolchest. It consists of a
meillo@32: set of tools, each covering a specific task of email handling. The programs
meillo@8: operate on a common mail storage. The specific format of the mail storage
meillo@32: characterizes MH in the same way like the format of the file system
meillo@32: characterizes Unix.
meillo@32: The mail storage consists of \fImail folders\fP (directories) and
meillo@32: \fPmessages\fP (regular files).
meillo@32: Each message is stored in a separate file in the format it had been
meillo@32: received (i.e. transfer format). The files are named with ascending numbers
meillo@32: in each folder.
meillo@32: MH tools maintain a \fIcontext\fP, which includes
meillo@32: the current mail folder and current message.
meillo@32: Processes in Unix have a similar context, containing the current working
meillo@32: directory, for instance. In contrast, the process context is maintained
meillo@32: by the Unix kernel automatically, whereas MH tools need to maintain the MH
meillo@32: context themselves.
meillo@32: The user can have one MH context or multiple ones, he can even share it
meillo@32: with other users.
meillo@32: Messages can have symbolic names. These can be automatically updated
meillo@32: position names like being the next or the last message,
meillo@32: or user-settable group names for arbitrary sets of messages.
meillo@32: These names are called sequences.
meillo@32: Sequences can be bound to the folder or to the context.
meillo@2: .P
meillo@32: New MH tools are built out of or on top of existing ones easily \(en
meillo@32: a property common to toolchests.
meillo@32: Multiple versions of the same command with different default values
meillo@32: are created very easily. This provides shortcuts and tayloring.
meillo@32: Form templates for new messages or for replies are easily exchangable.
meillo@32: Generally, output is adjustable with format files.
meillo@32: The configuration is stored in a file that is called the user's \fIprofile\fP.
meillo@32: MH encourages the user to taylor and automate the mail handling.
meillo@32: Almost everypart of the system can be adjusted to personal preference.
meillo@32: The system is well scriptable and extendable.
meillo@32: As the MH toolchest was modelled after the Unix toolchest, the
meillo@32: properties of the latter apply to the former as well.
meillo@8: 
meillo@32: .U2 "Versions
meillo@27: .P
meillo@27: Three versions of MH are available today:
meillo@32: .IP "Old MH"
meillo@32: In most cases this version had been replaced by nmh,
meillo@32: but some systems might still provide old MH.
meillo@32: The main reasons to still use old MH are historical reasons.
meillo@32: MH provides hardly any benefits over nmh.
meillo@27: The development of old MH has stopped after the 6.8.4 release in
meillo@27: February 1996.
meillo@32: .IP nmh\0
meillo@27: The most widespread version of MH was forked off version 6.8.3 in December
meillo@32: 1996. It is based on the \fILBL changes\fP.
meillo@32: Backward-compatibility to old MH is provided by having new featues deactivated
meillo@32: by default. In consequence, the user needs to activate them explicitely to
meillo@32: be able to use them.
meillo@32: Throughout the previous years, the work on nmh was mostly maintenance work.
meillo@32: Development revived in December 2011 and stayed busy since then.
meillo@32: .IP mmh
meillo@32: This descendent of nmh is the subject of this thesis.
meillo@32: It had started as an experimental version, but became de facto a fork.
meillo@8: 
meillo@27: .U2 "Example Session
meillo@27: .P
meillo@32: Following is an example mail handling session with mmh.
meillo@32: It should be mostly compatible with nmh and old MH.
meillo@32: Details might vary but the look'n'feel is the same.
meillo@32: .P
meillo@32: XXX shell mail handling session follows ...
meillo@27: 
meillo@27: 
meillo@28: .H1 "nmh: Code and Community
meillo@2: .P
meillo@8: In order to understand the state, goals and dynamics of a project,
meillo@8: one needs to know its history. MH comes from a time before the
meillo@8: Internet, a time before networking became universal, a time when
meillo@8: emailing was small, short and simple. Then it grew, spread and
meillo@8: adopted to the changes. The core-concepts, however, remained the
meillo@8: same. During the XXX a small group of students at the University of
meillo@8: California, actively worked on MH. They added features and optimized,
meillo@8: like it is common for scientific work. This is still in pre-ANSI C
meillo@8: times. The source code contains many ancient parts. Code constructs
meillo@8: specific to BSD or hardware of that time are usual.
meillo@2: .P
meillo@8: Nmh started eight years after the ANSI C standard had been
meillo@8: established. A more modern coding style entered the code base. Still
meillo@8: a part of the developers come from ``the old days''. The developer
meillo@8: base became more diverse and thus the code. Programming practices
meillo@8: from different decades merged into the project. Different coding
meillo@8: styles came together. It appears as if multiple peers added code
meillo@8: parts, resulting in a conclomeration rather than an homogenic
meillo@8: of-one-cast mail system. Still, the basic concepts hold it together.
meillo@8: They were mostly untouched throughout the years.
meillo@8: .P
meillo@8: Although, at the surface, nmh is a toolchest, meaning a collection
meillo@8: of completely modularized small programs, on the source code level,
meillo@8: it is much more interweaved. Parts of the basic functions are
meillo@8: collected in a MH standard library, which is good, but often
meillo@8: separate functions are compiled into programs, for effiency reasons.
meillo@8: This lead to intricate innards.
meillo@8: The advent of MIME rose the complexity of email by a magnitude. This
meillo@8: is visible in nmh. The MIME-related parts are the most complex ones.
meillo@8: It's also visible that MIME support had been added on top of the
meillo@32: old MH later. The MH style made this easily possible, but it
meillo@8: also lead to duplicated functions (e.g. \fLshow\fP, \fLmhshow\fP)
meillo@8: and had not been thoroughly included into the concepts (e.g. the
meillo@8: user-visible access to whole messages and MIME parts are inherently
meillo@8: different).
meillo@8: .P
meillo@8: For compatibility's sake, it is a common understanding to have the
meillo@8: default settings to be compatible, requiring any new feature to be
meillo@8: explicitely enabled. This puts a burden on new users, because nmh
meillo@8: out-of-the-box keeps staying in the same ancient style, where users
meillo@8: usually want to have it practical for modern emailing.
meillo@8: But of course, this depends on if nmh is seen to be a front-end or a
meillo@8: back-end.
meillo@8: 
meillo@8: 
meillo@27: .H1 "mmh
meillo@28: .P
meillo@28: I started to work on my experimental version, which I call
meillo@28: \fImmh\fP (for \fImeillo's mail handler\fP), in Fall 2011.
meillo@28: In December, when I announced that I would work on an experimental
meillo@28: version, the activity in nmh suddenly rose. Suddently the community
meillo@28: started to move.
meillo@28: After long years of mostly idling, nmh became actively developed again.
meillo@28: What a great result!
meillo@28: Hence, while I was working on mmh, the community was working on nmh
meillo@28: too. My own work went in parallel and mostly unrelated.
meillo@28: .P
meillo@28: Because of several circumstances, my experimental version is rather
meillo@28: a fork today, although this may change again in the future.
meillo@27: 
meillo@27: .U2 "Motivation
meillo@27: .P
meillo@27: XXX
meillo@27: 
meillo@27: .U2 "Why it is worth it
meillo@27: .P
meillo@27: XXX
meillo@27: 
meillo@27: .U2 "Target Field
meillo@27: .P
meillo@27: XXX Target field and scenarios
meillo@27: .P
meillo@27: The target user in mind likes Unix and its philosophy.
meillo@27: He likes to use programs that are conceptionally appealing.
meillo@27: He's familiar with the command line and enjoys its power.
meillo@27: He is at least capable of shell scripting and wants to improve his
meillo@27: productivity by scripting the mail system.
meillo@27: His computer and operating system are from post-ANSI C times.
meillo@27: He likes to attach files, exchanges text containing non-ASCII
meillo@27: characters, signs or encrypts his messages.
meillo@27: He does not use bulletin boards anymore, nor non-mbox style mail
meillo@27: drops, nor does he rely on compatibility to nmh.
meillo@27: He already has and MTA/MSA and MRA running or is able to set them
meillo@27: up.
meillo@27: He does not want to have to read a book in order to make his MUA
meillo@27: usable.
meillo@27: .P
meillo@27: XXX Limitations
meillo@27: 
meillo@27: .U2 "The Vision
meillo@8: .P
meillo@8: The general goals of the mmh project are the following:
meillo@8: .BU
meillo@8: I believe that mmh should be perfectly suited for modern emailing,
meillo@8: out-of-the-box.
meillo@8: .BU
meillo@8: I care less about compatibility and more about conceptionally elegant
meillo@8: approaches.
meillo@8: .BU
meillo@8: I care for general, clear, and simple concepts.
meillo@8: .BU
meillo@8: I like to create an of-one-style email system. It should feel like
meillo@8: cast as one.
meillo@8: .BU
meillo@8: I plan to remove any optimizations that rises obscurity, unless it
meillo@8: appears to be neccessary to make mmh usable at all.
meillo@8: 
meillo@27: .U2 "Work to do
meillo@8: .BU
meillo@27: Remove the MTA and MRA facilities. Mmh shall concentrate on the MUA
meillo@8: task. Mail shall enter mmh's mail storage via the system mail drop
meillo@8: and it shall leave mmh via the local \fLsendmail\fP command.
meillo@8: .BU
meillo@8: Remove any further functions that are not related to mmh's main task.
meillo@8: Bulletin board support is on example. Also remove support for ancient 
meillo@8: technologies, like hardcopy terminals.
meillo@8: .BU
meillo@8: Refactor the source code to meet modern style criteria. Use
meillo@8: standardized library functions when possible.
meillo@8: .BU
meillo@8: Replace performance optimizations by clear and readable code.
meillo@8: .BU
meillo@8: Reduce the feature set to the commonly used one, removing
meillo@8: corner-cases. Set sane default values.
meillo@8: .BU
meillo@8: Add better attachment support. Add support for digital signatures and
meillo@8: encryption.
meillo@8: .BU
meillo@8: Merge \fLshow\fP and \fLmhshow\fP into one single mail display program.
meillo@8: Integrate MIME support deeper and more natural into MH.
meillo@8: .BU
meillo@8: Provide a ready-to-use setup out-of-the-box.
meillo@27: 
meillo@27: 
meillo@27: .H1 "Goals of this Thesis
meillo@27: 
meillo@27: .U2 "Methods
meillo@27: .P
meillo@27: foo