meillo@92: \chapter{Market analysis}
meillo@105: \label{chap:market-analysis}
meillo@92: 
meillo@375: This chapter analyzes the current situation and future trends for electronic communication in general and for email in particular. First email's position within other electronic communication technologies is located. Then trends for the whole field of electronic communication are shown. Afterwards opportunities and threats in the market and trends for email are identified. The insights of these analysis result in a summary of things that are important for developing future-proof email software.
meillo@92: 
meillo@92: 
meillo@92: 
meillo@105: \section{Electronic communication technologies}
meillo@92: 
meillo@392: Electronic communication is ``communication by computer'', according to the \name{WordNet} database of the \name{Princeton University} \citeweb{wordnet}. Mobile phones and fax machines should be seen as computers here, too. The \name{Science Glossary} of the \name{Pennsylvania Department of Education} \citeweb{science-glossary-pa} describes electronic communication as ``System for the transmission of information using electronic technology (e.g., digital cameras, cellular telephones, Internet, television, fiber optics).''
meillo@402: \index{fax}
meillo@391: \index{electronic communication}
meillo@92: 
meillo@375: Electronic communication needs no transport of tangible things, only electrons, photons, or radio waves need to be transmitted. Thus electronic communication is fast in general. With costs mainly for infrastructure and very low costs for data transmission is electronic communication also cheap communication. Primary the Internet is used as underlying transport infrastructure. Thus electronic communication is available nearly everywhere around the world. These properties---fast, cheap, available---make electronic communication well suited for long distance communication.
meillo@92: 
meillo@224: As globalization proceeds and long distance communication becomes more and more important, the future for electronic communication is bright.
meillo@92: 
meillo@375: Electronic communication includes the following technologies: electronic mail (email), Instant Messaging (\NAME{IM}), chats (e.g.\ \NAME{IRC}), short message service (\NAME{SMS}), multimedia message service (\NAME{MMS}), voice mail, video messages, and Voice over \NAME{IP} (\NAME{VoIP}).
meillo@92: 
meillo@92: 
meillo@105: \subsection{Classification}
meillo@391: 
meillo@375: Electronic communication technologies can be divided in synchronous and asynchronous communication. Synchronous communication is direct dialog with little delay. Telephone conversation is an example. Asynchronous communication consists of independent messages. Dialogs are possible as well, but not in the same direct fashion. These two groups can also be split by the time which is needed for data delivery. Synchronous communication requires nearly real-time delivery, whereas for asynchronous communication message delivery times of several seconds or minutes are sufficient.
meillo@402: \index{electronic communication!classification}
meillo@92: 
meillo@395: Another possible separation is to distinguish recorded and written information. Recorded information, like audio or video data, is accessible only in a linear way by spooling and replay. Written information, on the other hand, can be accessed in arbitrary sequence, detail, and speed.
meillo@114: 
meillo@375: \person{Lenke} and \person{Schmitz} use the same criteria to classify \emph{new media} \cite{lenke95}. They additionally divide into local and remote communication---the latter is presumed here---and by the number of communication participants. A classification by participant structure is omitted here, as communication technologies for many-to-many communication (like chat rooms) are usable for one-to-one (private chat) too, and ones for one-to-one (email) are usable for many-to-many (mailing lists).
meillo@92: 
meillo@395: Figure~\ref{fig:comm-classification} shows a classification of communication technologies by the properties synchronous/asynchronous and written/recorded. Email and \NAME{SMS} are examples for written and asynchronous communication; \NAME{IM} and chats are ones for written but synchronous communication. Voice mail and video messages stand as examples for recorded asynchronous communication. \NAME{VoIP} represents recorded synchronous communication.
meillo@92: 
meillo@211: \begin{figure}
meillo@105: 	\begin{center}
meillo@397: 		\includegraphics[scale=0.75]{fig/comm-classification.eps}
meillo@105: 	\end{center}
meillo@395: 	\caption{Classification of electronic communication technologies}
meillo@105: 	\label{fig:comm-classification}
meillo@105: \end{figure}
meillo@105: 
meillo@375: One might be surprised to find Instant \emph{Messaging} not in the group of \emph{message} communication. Instant Messaging could be put in both groups because it allows asynchronous communication additional to being a chat system. The reasons why it is classified as dialog communication are its primary use for dialog communication and the very fast---instant---delivery time.
meillo@211: 
meillo@375: Email is not limited to written information, at least not anymore since the advent of \NAME{MIME}, which allows to include multimedia content in textual email messages. Thus recorded information can be sent as sub parts of emails. The same applies to Instant Messaging too, where file transfer is an additional sub service offered by most systems. In general recorded information can be transmitted in an encoded textual form.
meillo@391: \index{mime}
meillo@211: 
meillo@105: 
meillo@105: 
meillo@105: 
meillo@105: \subsection{Life cycle analysis}
meillo@391: \index{life cycle analysis}
meillo@391: 
meillo@375: Life cycle analysis are common for products but also for technologies. This one here is for electronic communication technologies. The first dimension regarded is the life time of the subject. It is segmented into the introduction, growth, mature, saturation, and decline phases. The second dimension can display market share, importance, or similar values. The graph has always an S-line shape, with a slow start, a rapidly increasing first half, the highest level in the fourth fifths, and a slowly declining end. Reaching the end of the life cycle means that the subject gets superseded by successors or the market situation changed thus it is old-fashioned.
meillo@105: 
meillo@378: The current position on the life cycle of some selected communication technologies is shown in figure~\ref{fig:comm-lifecycle}. It is important to notice that the time dimension can be different for each technology---some life cycles are shorter than others---the shape of the graph, however, is the same.
meillo@105: 
meillo@105: \begin{figure}
meillo@105: 	\begin{center}
meillo@397: 		\includegraphics[scale=0.75]{fig/comm-lifecycle.eps}
meillo@105: 	\end{center}
meillo@105: 	\caption{Life cycle of electronic communication technologies}
meillo@105: 	\label{fig:comm-lifecycle}
meillo@105: \end{figure}
meillo@105: 
meillo@375: Video messages and voice mail are technologies in the introduction phase. Voice over \NAME{IP} is heavily growing these days. Instant Messaging has reached maturation and is still growing. Email is an example for a technology in the saturation phase. Telefax, for instance, is a declining technology.
meillo@402: \index{fax}
meillo@211: 
meillo@375: Email ranges in the saturation phase which is defined by a saturated market. No more products are needed: there is no more growth. This means, email is a technology which is used by everyone who want to use it. It is a standard technology. The current form of email in the current market is on the top of its life cycle. The future is decline, sooner or later.
meillo@105: 
meillo@378: But life cycles positions change as the subject or the market changes. An examples is the \name{Flash} animation software \citeweb{flash:homepage}. The product's change from a drawing and animation system to a technology for website creation, advertising, and movie distribution, and the thus changing target market, made it slip back on the life cycle. If the email system would evolve to become the basis for Unified Messaging (see section~\ref{sec:unified-messaging}), a similar slip back would be the consequence.
meillo@391: \index{um}
meillo@224: 
meillo@375: The \NAME{DVD} standards \NAME{DVD+} and \NAME{DVD$-$} are an example for a changing market. With the upcoming next generation formats \name{Blu-ray Disc} \citeweb{wikipedia:bluray} and \NAME{HD-DVD} \citeweb{wikipedia:hddvd}, a much sooner decline of \NAME{DVD+} and \NAME{DVD$-$} started, even before they reached their last improvement steps in storage size. Such can happen to email too, if Unified Messaging is a revolution to the email system instead of an evolution.
meillo@391: \index{um}
meillo@105: 
meillo@105: 
meillo@105: 
meillo@105: 
meillo@105: \subsection{Trends}
meillo@391: 
meillo@375: Following are the trends for electronic communication. They are shown from the view point of \MTA{}s. Nevertheless are these trends common for all of the communication technology.
meillo@391: \index{electronic communication!trends}
meillo@105: 
meillo@105: \subsubsection*{Consolidation}
meillo@391: 
meillo@375: There is a consolidation of communication technologies with similar transport characteristics going on, nowadays. Email is the most flexible kind of asynchronous communication technology in major use. Hence email is the best choice for transferring messages of any kind today. But in future it probably will be \name{Unified Messaging}, which tries to group all types of asynchronous messaging into one communication system. It aims to provide transparent transport for all kinds of content and flexible access interfaces for all kinds of clients. Unified Messaging seems to have the potential to be the successor of all asynchronous communication technologies, including email.
meillo@391: \index{um}
meillo@105: 
meillo@375: Today email still is the major asynchronous communication technology and it probably will be it for the next years. Unified Messaging needs similar transfer facilities as email, thus it seems to be rather an evolution to the current technology than a revolution. Hence \MTA{}s will still be of importance in future, though maybe in a modified form.
meillo@402: \index{mta}
meillo@105: 
meillo@105: 
meillo@105: \subsubsection*{Integration}
meillo@105: 
meillo@375: Integration of communication technologies becomes popular. This goes beyond consolidation, because communication technologies of different kinds are bundled together to make communication more convenient for human beings. User interfaces tend to go the same direction. The underlying technologies are going to get grouped. But it seems as if synchronous and asynchronous communication can not be joined together in a sane way, thus they will probably only merge at the surface.
meillo@105: 
meillo@105: 
meillo@105: \subsubsection*{Communication hardware}
meillo@105: 
meillo@400: Communication hardware comes from two different roots: On one side, the telephone, now available as mobile phones. This group centers around re\-cor\-ded data and dialog but messages are also supported by the answering machine and \NAME{SMS}. On the other side, mail and its relatives like email, which use computers as main hardware. This part centers around document messages but also supports dialog communication in Instant Messaging and Voice over \NAME{IP}.
meillo@105: 
meillo@375: The last years finally brought the two groups together, with \name{smart phones} being the merging hardware element. Smart phones are computers in the size of mobile phones or mobile phones with the capabilities of computers, however one likes to see it. They provide both functions by being telephones \emph{and} computers.
meillo@391: \index{smart phone}
meillo@105: 
meillo@375: Smart phones match well the requirements of recorded data for which they were designed. Text is difficult to write with their minimal keyboards, but speech to text converters may provide help in future. This leads to a need for ordinary computers for the field of exchanging text documents and as better input hardware for all written information.
meillo@105: 
meillo@375: It seems as if a combination of desktop computers and smart phones will be the hardware used for communication in future. Both specialized to the best matching communication technologies but with support for the others, too. Hence facilities for transferring information off and onto the devices will be needed.
meillo@105: 
meillo@105: 
meillo@114: \subsubsection*{Unified Communication}
meillo@391: \index{uc}
meillo@114: 
meillo@375: \name{Unified Communication} is the technology that aims to consolidate and integrate all electronic communication and to provide access for all kinds of hardware clients. Unified Communication tries to bring the three trends here mentioned together. The \NAME{PC} \name{Magazine} has the following definition in its Encyclopedia: ``[Unified Communications is t]he real-time redirection of a voice, text or e-mail message to the device closest to the intended recipient at any given time.'' \citeweb{pcmag:uc}. The main goal is to integrate all kinds of communication (synchronous and asynchronous) into one system, hence this requires real-time delivery of data.
meillo@114: 
meillo@375: According to \person{Michael Osterman}, Unified Communications is already possible as far as various incoming sources are routed to one storage where messages can be accessed by different clients \cite{osterman08}. But a system with an ``intelligent parser of a single data stream into separate streams that are designed to meet the real-time needs of the user'' is a goal for the future, he says.
meillo@375: 
meillo@375: The question is whether the integration of synchronous and asynchronous communication does make sense. A communication between one person talking on the phone and the other replying with an instant messenger, certainly does (assumed the text-to-speech and speech-to-text converting is fast and the quality good enough). But transferring large video messages with the same technology as real-time communication data, possibly does not.
meillo@114: 
meillo@114: 
meillo@114: 
meillo@114: \subsubsection*{Unified Messaging}
meillo@114: \label{sec:unified-messaging}
meillo@391: \index{um}
meillo@114: 
meillo@375: \name{Unified Messaging}, although often used exchangeable with Unified Communications, is only a subset of it. It does not require real-time data transmission and is therefore only usable for asynchronous communication \citeweb{wikipedia:uc}. Unified Messaging's basic function is: Receiving incoming messages from various channels, converting them into a common format, and storing them into a single memory. The stored messages can then be accessed from different devices \citeweb{wikipedia:um}.
meillo@375: 
meillo@375: The easiest way to implement Unified Messaging is to base it on either email and convert all input sources to email messages (as attachments for instance) and store them in the user's mailbox, or use the telephone system as basis and convert text messages to speech. Both is technically possible for asynchronous communication.
meillo@114: 
meillo@248: Finally, a critical voice from \person{Jesse Freund}, who voted Unified Messaging on top of a hype list, published by \name{Wired.com} ten years ago. His description of the technology ended with the humorous sentences:
meillo@375: 
meillo@224: \begin{quote}
meillo@224: Unified messaging is a nice idea, but a tough sell: The reason you bought a cell phone, a pager, and a fax/modem is because each does its job well. No one wants to download voice mail as a series of RealAudio messages or sit through a voice mail bot spelling out email, complete with `semicolon dash end-parenthesis' for ;-).
meillo@224: \hfill\cite{wired:hype}
meillo@224: \end{quote}
meillo@402: \index{fax}
meillo@114: 
meillo@114: 
meillo@105: 
meillo@105: 
meillo@105: 
meillo@105: 
meillo@105: \section{Electronic mail}
meillo@391: \index{email}
meillo@105: 
meillo@375: After viewing the whole market of electronic communication, a zoom into the market of electronic mail follows. Email is an asynchronous communication technology that focuses on the transport of textual information. The market situation for email is important, because this thesis is about an \MTA. Interesting questions are: Is email future-safe? How will electronic mail change? Will it change at all? Which are the critical parts? These questions matter when deciding the directions for further development of an \MTA. They are discussed in this section.
meillo@107: 
meillo@105: 
meillo@105: 
meillo@120: \subsection{SWOT analysis}
meillo@174: \label{sec:swot-analysis}
meillo@391: \index{swot analysis}
meillo@105: 
meillo@375: A \NAME{SWOT} analysis regards the strengths and weaknesses of a subject against the opportunities and threats of its market. The slightly altered form called \name{Dialectical} \NAME{SWOT} \name{analysis}, which is used here, is described in \cite{powerof2x2}. \NAME{SWOT} analysis should always focus on a specific goal which is to reach. In this case, the main goal is to make email future-safe.
meillo@105: 
meillo@375: The two dimension---the subject and the market---are regarded in relation to each other by the analysis. Here the analysis shall be driven by the market's dimension. Thus first threats of the market are identified and split into being strengths or weaknesses of email. Then the same is done for opportunities of the market.
meillo@391: \index{the market}
meillo@212: 
meillo@212: \subsubsection*{Threats}
meillo@248: The market's main threat is \emph{spam}, also named \name{junk mail} or \name{unsolicited commercial email} (\NAME{UCE}). \person{David~A.\ Wheeler} is clear about it:
meillo@391: \index{spam}
meillo@375: 
meillo@213: \begin{quote}
meillo@213: Since \emph{receivers} pay the bulk of the costs for spam (including most obviously their time to delete all that incoming spam), spam use will continue to rise until effective technical and legal countermeasures are deployed, \emph{or} until people can no longer use email.
meillo@218: \hfill\cite{wheeler03}
meillo@213: \end{quote}
meillo@375: 
meillo@400: The amount of spam is huge. Panda Security and Commtouch write in their \name{Email Threats Trend Report} for the second Quarter of 2008: ``Spam levels throughout the second quarter averaged 77\,\%, ranging from a low of 64\,\% to a peak of 94\,\% of all email [...]'' \cite[page 4]{panda:email-threats}. The report sees the main source of spam in bot nets consisting of zombie computers: ``Spam and malware levels remain high for yet another quarter, powered by the brawny yet agile networks of zombie \NAME{IP}s.'' \cite[page 1]{panda:email-threats}. This is supported by IronPort Systems: ``More than 80 percent of spam now comes from a `zombie'---an infected \NAME{PC}, typically in a consumer broadband network, that has been hijacked by spammers.'' \cite{ironport:zombie-computers}. Positive for \MTA{}s is that they are not the main source for spam, but it is only a small delight. Spam is a general weakness of the email system because it is not stoppable.
meillo@402: \index{spam!sources}
meillo@212: 
meillo@213: 
meillo@213: 
meillo@105: 
meillo@126: 
meillo@212: \subsubsection*{Opportunities}
meillo@192: 
meillo@395: Opportunities of the market are large data transfers, originating in multimedia content, which becomes popular. If email is used as basis for Unified Messaging, lots of voice and video mail will be transferred. Email is weak related to this kind of data: The data needs to be encoded to \NAME{ASCII} which stresses mail servers a lot. Additionally a lot of traffic is generated by the \name{store-and-forward} transfer, which \SMTP\ uses.
meillo@402: \index{ascii}
meillo@391: \index{um}
meillo@402: \index{smtp!store-and-forward}
meillo@192: 
meillo@396: The use of different hardware to access mail is another opportunity of the market. But as more hardware gets involved, the networks become more complex. Thus the need for more software and infrastructure to transfer mail within the growing network might be a weakness of the email system.
meillo@114: 
meillo@396: An opportunity of the market and at the same time a strength of electronic mail is its standardization. Few other communication technologies are standardized, and thus freely available, in a similar way. Another opportunity and strength is the modular and extensible structure of electronic mail; it can easily evolve to new requirements.
meillo@391: \index{email!standardiziation}
meillo@105: 
meillo@375: The increasing integration of communication channels is an opportunity for the market. But deciding whether it is a weakness or strength of email is difficult. Due to the impossibility to integrate synchronous stream data and large binary data, it is a weakness. But it is also a strength, because arbitrary asynchronous communication data already can be integrated. On the other hand, the integration might be a threat too, because integration often leads to complexity of software. Complex software is more error prone and thus less reliable. This, however, could again be a strength of electronic mail because its modular design decreases complexity.
meillo@105: 
meillo@403: Figure~\ref{fig:email-swot} displays the \NAME{SWOT} analysis in a handy overview. It is obvious to see, that the opportunities outweigh. This is an indicator for a still increasing market.
meillo@402: \index{swot analysis}
meillo@105: 
meillo@105: \begin{figure}
meillo@105: 	\begin{center}
meillo@397: 		\includegraphics[scale=0.75]{fig/email-swot.eps}
meillo@105: 	\end{center}
meillo@120: 	\caption{\NAME{SWOT} analysis for email}
meillo@105: 	\label{fig:email-swot}
meillo@105: \end{figure}
meillo@105: 
meillo@391: 
meillo@213: \subsubsection*{Resulting strategies}
meillo@212: 
meillo@375: The result of a \NAME{SWOT} analysis is a set of strategies that advice how to best react on the identified opportunities and threats, dependent on whether they are strengths or weaknesses of the subject. These strategies are what should be done to achieve the overall goal---here making email future-safe.
meillo@212: 
meillo@375: Threats of the market that are weaknesses of the subject should be avoided if possible, or one should prepare against them if they are impossible to avoid. As spam is unavoidable, email must prepare against it. The goal is to reduce spam to a bearable level. Spam fighting, with currently used protocols, is a war where the good guys must lose. Investing high effort will result in few gain. Hence enough spam protection should be provided, but not more. New concepts and protocols will change this fight; they must be in use before email has become unusable.
meillo@212: 
meillo@375: Threats that are strengths of the subject should be confronted. Here none were identified.
meillo@212: 
meillo@375: For opportunities of the market that are weaknesses of the subject, solutions should be searched. Large data transfers and infrastructures with nodes that move within the network, are of such kind. As a lot of potential is available, it should be used to develop solutions, to remove the weaknesses.
meillo@212: 
meillo@212: Finally, opportunities that are strengths of the subject. These are standardization, modularity, and extendability. They should be exploited to go even further, these are the key advantages of email.
meillo@212: 
meillo@105: 
meillo@105: 
meillo@105: 
meillo@92: 
meillo@92: \subsection{Trends for electronic mail}
meillo@298: \label{sec:email-trends}
meillo@391: \index{email!trends}
meillo@92: 
meillo@375: Nothing remains the same, neither does the email technology. Emailing in future will probably differ from emailing today. This section tries to identify possible trends that affect the future of electronic mail.
meillo@105: 
meillo@105: 
meillo@107: \subsubsection*{Provider independence}
meillo@391: 
meillo@403: Today's email structure is heavily dependent on email providers. This means, most people have email addresses from some provider. These can be providers that offer email accounts in addition to their regular services, for example online connections. \NAME{AOL} and \name{T-Online} for instance do so. Or specialized email providers that commonly offer free mail as well as enhanced mail services for which one has to pay. Examples for specialized email providers are \NAME{GMX} and \name{Yahoo}.
meillo@391: \index{mail provider}
meillo@92: 
meillo@375: Outgoing mail is send either with the web mail client of the provider or by using an \MUA\ which sends it to the provider for relay. Incoming mail is read with the web mail client or retrieved from the provider via \NAME{POP3} or \NAME{IMAP} to the local computer to be read using the \MUA. This means all mail sending and receiving work is done by the provider.
meillo@391: \index{pop3}
meillo@391: \index{imap}
meillo@391: \index{mua}
meillo@92: 
meillo@375: The reason therefore is originated in the time when people used dial-up connections to the Internet. A mail server needs to be online to receive email. Sending mail is no problem, but receiving it is hardly possible with an \MTA\ which is few time online. Internet service providers had servers that were all day long connected to the Internet. So they offered email service, and they still do.
meillo@391: \index{dial-up}
meillo@391: \index{isp}
meillo@92: 
meillo@402: Nowadays, dial-up Internet access became rare; the majority of the users has broadband Internet access. As a flat rate is payed for it, the time being online does not affect costs anymore, even traffic is unlimited. Today it is possible to have an own mail server running at home. The remaining technical problem is the changing \NAME{IP} addresses one gets assigned every 24 hours\footnote{At least this is the situation in Germany.}. But this is solvable with one of the dynamic \NAME{DNS} services; they provide the mapping of a fixed domain name to the changing \NAME{IP} addresses.
meillo@402: \index{dynamic dns}
meillo@92: 
meillo@392: Home servers become popular for central data storage and multimedia services, these days. Being assembled of energy efficient hardware, power consumption is no big problem anymore. These home servers will replace video recorders and \NAME{CD} music collections in the near future. It is also realistic that they will manage heating systems and intercoms, too. Given the future leads to this direction, it will be a logical step to have email and other communication provided by the own home server as well.
meillo@391: \index{home server}
meillo@213: 
meillo@375: After years in which \MTA{}s have not been popular for users, the next years might bring the \MTA{}s back to the users. Maybe in a few years nearly everyone will have one, or many, running at home.
meillo@92: 
meillo@92: 
meillo@92: \subsubsection*{Pushing versus polling}
meillo@391: \index{push email}
meillo@92: 
meillo@375: The retrieval of email is a field that is also about to change these days. The old way is to fetch email by polling the server that holds the personal mailbox. This polling is normally done in regular intervals, often once every five to thirty minutes. The mail transfer from the mailbox to the \MUA\ is initiated from the user side. The disadvantage herewith is the delay between the arrival of mail on the server and the time when the user finally has the message on his screen.
meillo@402: \index{mua}
meillo@92: 
meillo@396: To remove this disadvantage, \name{push email} \citeweb{pushemail.co.uk} was invented. Here the server is not polled every few minutes about new mail, but the server pushes new mail directly to the client on arrival. The transfer is initiated by the server. This concept became popular with smart phones; they were able to do emailing but the traffic caused by polling the server was expensive.
meillo@375: 
meillo@375: The concept works well with mobile phones where the provider knows about the client, but it does not seem to be a choice for computers, since the provider needs to have some kind of login to push data to the user's computer. Push email, however, could swap over to computers when using a home server and no external provider. A possible scenario is a home server which receives mail from the Internet and pushing it to own workstations and smart phones. The configuration could be done by the user by using some simple interface, like one configures his telephone system to have different telephone numbers ringing on specified phones.
meillo@402: \index{configuration}
meillo@92: 
meillo@375: Another problem is when multiple clients share one mailbox. This is only solvable by working directly in the server's mailbox, which causes lots of traffic, or by storing at least information about read messages and the like there.
meillo@105: 
meillo@126: 
meillo@213: \subsubsection*{New email concepts}
meillo@92: 
meillo@396: Changing requirements for email communication lead to the need for new concepts and new protocols that cover these requirements. One of these concepts to redesign the email system is named \name{Internet Mail 2000} \citeweb{im2000}. It was proposed by \person{Daniel~J.\ Bernstein}, the creator of \qmail. Similar approaches were independently introduced by others, too.
meillo@391: \index{Internet Mail 2000}
meillo@92: 
meillo@396: As main change, the sender has the responsibility for mail storage; only a notification about a mail message gets sent to the recipient. The recipient can then fetch the message then from the sender's server. This is in contrast to the \SMTP\ mail architecture where mail and the responsibility for it is transferred from the sender to the receiver. (See page~\pageref{smtp-intro} for the \name{store-and-forward} principle.)
meillo@391: \index{smtp!store-and-forward}
meillo@402: \index{smtp!responsibility}
meillo@92: 
meillo@375: \MTA{}s are still important in this new email architecture, but in a slightly different way. They do not transfer mail itself anymore, but they transport the notifications about new mail to the destinations. This is a quite similar job as in the \NAME{SMTP} model. The real transfer of the mail, however, can be done in an arbitrary way, for example via \NAME{FTP} or \NAME{SCP}.
meillo@212: 
meillo@400: A second concept, this one primary to arm against spam, is \person{David~A.\ Whee\-ler}'s \name{Guarded Email} \cite{wheeler03}. It requires messages to be recognized as Ham (non-spam) to be accepted, otherwise a challenge-response authentication will be initiated.
meillo@391: \index{Guarded Email}
meillo@212: 
meillo@375: \name{Hashcash} by \person{Adam Back}---a third concept---tries to limit spam and denial of service attacks \cite{back02}. It requests payment for email. The costs are computing time for the generation of hash values. Thus sending spam becomes expensive. Further information about \name{Hashcash} can be found on \citeweb{hashcash:homepage}.
meillo@402: \index{denial of service attack}
meillo@391: \index{Hashcash}
meillo@212: 
meillo@375: New concepts, like the ones presented here, are invented to remove problems of the email technology. \name{Internet Mail 2000}, for instance, removes the spam problem and the problem of large message transfers.
meillo@126: 
meillo@92: 
meillo@92: 
meillo@105: 
meillo@114: 
meillo@114: 
meillo@375: \subsection{Important properties in future}
meillo@126: \label{sec:what-will-be-important}
meillo@92: 
meillo@375: \paragraph{Easy configuration}
meillo@375: Provider independence through running an own mail server at home asks for easy configuration of the \MTA. Providers have specialists to configure the systems, but ordinary people do not. Solutions are either having some home service system for computer configuration established with specialists coming to ones home to set up the systems; like it is already common for problems with the power and water supply systems. Or configuration needs to be easy and fool-proof, so it can be done by the owner himself. The latter solution depends on standardized parts that fit together seamlessly. The technology must not be a problem itself. Only settings that are custom to the users environment should be left open for him to set. This of course needs to be doable using a simple configuration interface like a web interface. Non-technical educated users should be able to configure the system.
meillo@402: \index{configuration}
meillo@92: 
meillo@396: Complex configuration itself is not a problem if simplification wrappers provide an easy interface. The approach of wrappers to make it look easier to the outside is a good concept in general. It still lets the specialist do complex and detailed configuration while also a simple configuration interface to novices is offered. \sendmail\ took this approach with the \name{m4} macros \cite{sendmail:config}. Further more is this approach well suited to provide various wrappers with different user interfaces (e.g.\ graphical programs, websites, command line programs; all of them either in a questionnaire style or interactive).
meillo@402: \index{sendmail}
meillo@402: \index{wrapper}
meillo@402: \index{m4 macros}
meillo@92: 
meillo@375: \paragraph{Performance}
meillo@375: When \MTA{}s become popular on home servers and maybe even on workstations and smart phones, then performance will be less important. Providers need \MTA{}s that process large amounts of mail in short time. There is no need for home servers and workstations to handle that much mail; they need to process far less email messages per time unit. Thus performance will probably not be a main requirement for an \MTA\ in future, given they mainly run on private machines.
meillo@391: \index{performance}
meillo@92: 
meillo@375: \paragraph{Flexibility}
meillo@378: New mailing concepts and architectures like push email or \name{Internet Mail 2000} will, if they succeed, require \MTA{}s to adopt the new technology. \MTA{}s that are not able to change are going to be sorted out by evolution. Thus it is important \emph{not} to focus too much on one use case, but to stay flexible. \person{Allman} saw the flexibility of \sendmail\ one reason for its huge success (see section~\ref{sec:sendmail}).
meillo@402: \index{sendmail}
meillo@391: \index{flexibility}
meillo@92: 
meillo@375: \paragraph{Security}
meillo@375: Another important requirement for all kinds of software is security. There is a constant trend coming from completely non-secured software, in the 70s and 80s, over growing security awareness, in the 90s, to security being a primary goal, now. This leads to the conclusion that software security will be even more important within the next years. As more clients get connected to the Internet and especially more computers are listening for incoming connections (like an \MTA\ in a home server), there are more possibilities to break into systems. Securing of software systems will require increasing effort in future.
meillo@391: \index{security}
meillo@92: 
meillo@375: \paragraph{Out-of-the-box usage}
meillo@375: \name{Plug-and-play}-able hardware with preconfigured software can be expected to become popular. Like someone buys a set-top box to watch Pay-\NAME{TV} today, he might be buying a mail server box in a few years. He plugs the power cable in, inserts his email address in a web interface, and selects the clients (computers or smart phones) to which mail should be send and from which mail is accepted for relay. That's all. It would just work then, like everyone expects it from a set-top box today. Secure and robust software is a precondition for such boxes to make this vision possible.
meillo@391: \index{out-of-the-box usage}
meillo@92: 
meillo@92: 
meillo@92: 
meillo@92: 
meillo@375: In summary: Easy configuration, as well as the somehow opposed flexibility, will be important for future \MTA{}s. Also will it be security, but not performance. \MTA{}s might become more commodity software, like web servers already are today, with the purpose to include it in many systems and the need of minimal configuration.
meillo@92: 
meillo@133: 
meillo@213: 
meillo@213: 
meillo@213: 
meillo@213: 
meillo@375: 
meillo@375: 
meillo@375: \section{Summary}
meillo@295: \label{sec:market-analysis-conclusion}
meillo@375: 
meillo@213: It seems as if electronic mail or a similar technology has good chances to survive the next decades.
meillo@213: 
meillo@375: \paragraph{Asynchronous communication}
meillo@375: It is assumed that it always will be important to send information messages. Those can be notes from people or notifications from systems. No other current available communication technology is as suitable for this kind of information transfer, as email, \NAME{SMS}, voice mail, or any other asynchronous communication technology. Synchronous communication, in contrast, is focused on dialog and typically interrupts people. The here needed kind of messages should not interrupt people, unless urgent, and they do not need two-way information exchange. Although synchronous communication could be used for transferring messages, it is not the best choice. The best choice is an asynchronous technology. Thus at least one asynchronous communication technology is likely to survive.
meillo@213: 
meillo@375: \paragraph{Email and Unified Messaging}
meillo@375: Whether email will be the surviving one, is not possible to know by now. It currently seems likely that Unified Messaging will be the future for asynchronous communication. But Unified Messaging is more a concept than a technology itself. This concept will base upon one or many underlying transport technologies, like email, \NAME{SMS}, and the like. Its goal is to integrate the transport technologies in order to hide them from the user's view. Currently, email is the most used asynchronous electronic communication technology. It is matured, flexible, and extendable, as well as standardized. These advantages make email a good base transport technology for Unified Messaging. Anyhow, whether email will be the basis for Unified Messaging or not, \MTA{}s are a software which is needed for all asynchronous communication methods: programs that transfer messages from senders to recipients.
meillo@213: 
meillo@375: \paragraph{Unified Communication}
meillo@375: Unified Communication, as next step after Unified Messaging, is about the integration of synchronous and asynchronous communication channels. It seems \emph{im}possible to merge the two worlds on basis of email in an evolutionary way. As only a revolutionary change of the whole email concept would make that merge possible, it is best to ignore it. New designed technologies are usually superior to heavily patched and bent old technologies, anyway. A general merge of synchronous and asynchronous communication has good chances to be fatal for email.
meillo@213: 
meillo@213: Until Unified Communication will become reality---if ever---electronic mail has a good position, also as basis for Unified Messaging.
meillo@213: 
meillo@396: \paragraph{\NAME{SWOT} analysis}
meillo@375: Not only the market influences email's future safety, but also must the email technology itself evolve to satisfy upcoming needs. Actions to take were discovered by using the \NAME{SWOT} analysis. These are: Prepare against spam. Search solutions for large data transfers and increasing growth and ramification of networks. Exploit standardization, modularity, and extendability.
meillo@402: \index{swot analysis}
meillo@213: 
meillo@375: \paragraph{Trends}
meillo@375: Also needed is awareness for new trends like: Provider independence, new delivery concepts, and completely new emailing concepts that introduce new protocols. Easy configuration, as well as the somehow opposed flexibility, will be important, but not performance. Security will be essential.
meillo@213: 
meillo@213: 
meillo@375: What kinds of \MTA{}s will be needed in future? Probably ones running on home servers and workstations. This is what \masqmail\ was designed for. The dial-up Internet connections, which are central to \masqmail's design, become rare, but mobile clients that move between different networks do need similar concepts, too. This makes \masqmail\ still be a good \MTA\ for such usage. Additionally, \masqmail\ is small and it is much easier to configure for setups that are common to workstations and home servers, than other \MTA{}s.
meillo@213: 
meillo@375: \MTA{}s might become more commodity software, like web servers already are today, with the purpose to be included in many systems with only minimal configuration.
meillo@402: \index{configuration}
meillo@375: 
meillo@375: 
meillo@396: \masqmail\ is a valuable program for various situations. Some setups became rare, but others are expected to become popular in the next years. It is expected that \masqmail's niche will rather grow than shrink.
meillo@213: 
meillo@213: 
meillo@213: 
meillo@213: 
meillo@213: 
meillo@213: 
meillo@213: % what about dial-up and other masqmail stuff?
meillo@213: % how good is masqmail suited?
meillo@213: % how large is the niche?
meillo@213: % is it growing?