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@pageheading(left "Diversity in Mail Use",
             center "", 
             right "Mackay")
@pagefooting(center "@value(page)")

@heading(Diversity in the Use of Electronic Mail:  A Preliminary Inquiry)
	      
@begin(center,size=12,facecode b)
Wendy E. Mackay

@i[Massachusetts Institute of Technology]
@i[1 Amherst Street]
@i[Cambridge, Massachusetts  02139]
@end(center)

@skip[2]
@center{@subheading[Abstract]}
@skip[1]

This paper describes a series of interviews that focus on the ways
that professional office workers use electronic mail to manage their
daily work.  A number of implications for the design of flexible mail
systems are discussed.

Two principal claims are made.  First, electronic mail is more than
just a communication system.  In addition to supporting information
management, it provides a mechanism for supporting a variety of time
management and task management activities.  Some people are
@i[prioritizers], concentrating on the problem of managing incoming
messages.  Others are @i[archivers], concentrating on how to archive
information for subsequent use.  Similarly, some people use mail to
@i[delegate] tasks, while others @i[perform] tasks delegated to them
by others electronically.

The second claim is that use of electronic mail is strikingly diverse,
although not infinitely so.  Individuals vary in their preferences,
both in their general willingness to manage their work electronically
and in their specific preferences along the dimensions described
above.  This diversity implies that one's own experiences with
electronic mail are unlikely to provide sufficient understanding of
other's uses of mail.  Mail designers should thus seek flexible
primitives that capture the important dimensions and provide
flexibility for a wide range of users.

@newpage

@subheading[Introduction]
@skip[1]

In a growing number of corporations, electronic mail has become an
essential form of communication.  As the number of people with access
to electronic mail increases, the benefits to individuals increase
accordingly.  Now that several organizations have more than a decade
of experience with electronic mail, it is useful to examine how mail
use has evolved and what additional capabilities would best support 
the needs of users.

Other studies have already demonstrated a number of substantial
effects of electronic mail.  It can solve certain kinds of problems,
such as increase the speed of decision making @cite(Crawford) or
enable the exchange of new information @cite(Feld, Sproull).
Electronic mail can also create new problems, most notably
"information overload" @cite(Denning, Malone2, Hiltz).  Sometimes
there are both positive and negative effects, such as changes in
organizational structure @cite(Rand, Crowston).

What is the total effect of these changes and how does it affect the
ways that individuals and groups perceive mail?  When presented with
the opportunity both to address problems created by mail and to use
mail to solve other problems, what do users do?  When presented with a
system such as the Information Lens @cite[Malone3], which provides
users with the ability to write personal rules for managing electronic
mail messages, what kinds of rules do people choose to write?  How do
these rules reflect the ways in which people use mail in their work?

This study describes a series of interviews that identifies existing
patterns of mail use and desired improvements, both in terms of
managing mail itself and in using mail to manage other activities.
This analysis grew out of data from interviews prior to a study of the
Information Lens.  The goal was to discover the ways in which people
used mail to address problems.  Exploring innovative uses of mail
generated within a mature electronic mail environment may help us to
better understand how to expand the capabilities of electronic
communication systems to facilitate collaborative work.

@skip[1]
@subheading(Interviews)
@skip[1]

Members of a large research laboratory (approximately 60 people)
within a major corporation were told about a study of the Information
Lens.  Individuals were asked to send electronic mail to the sponsors
of the study if they were interested in participating.  This paper
describes interviews conducted with members of this laboratory and is
primarily concerned with current and desired uses of electronic mail.
These interviews were conducted just prior to the introduction of
Lens; the study of how people actually use Lens is still in progress.

The Information Lens is a prototype electronic mail system developed
at MIT and designed primarily to help users filter and organize
electronic mail @cite(Malone3).  Lens uses semi-structured messages
which have predefined fields, such as @c[date:] or @c[Meeting
Location:], as well as open-ended text areas.  Users can create their
own sets of @c[IF-THEN] rules and Lens will process incoming messages
according to those rules.  The rules can perform various operations,
such as moving a message to a mail folder or adding information to a
calendar program.  Lens rules can also be used to identify
characteristics of "interesting messages".  One individual may write a
rule that will fire if a particular message meets certain criteria.
If another person creates such a message and addresses it to "anyone",
the first user will receive it automatically.

The explanation of Lens caused people to critically examine their
personal use of mail and served to focus attention on particular kinds
of problems.  Because Lens provided scenarios for solving these
problems, people were able to apply these ideas to problems in their
own work.  Although individuals were attracted to different Lens
features, the overall explanation of Lens provided a common ground for
discussion.

@skip[1]
@subheading(Participants)
@skip[1]

The 18 individuals who were interviewed for this study included people
with a broad range of jobs within the research laboratory.  15 were
full-time researchers and 3 were managers.  Of the researchers, 6 were
trained as computer scientists and 9 were trained in physics, psychology,
anthropology, or sociology.  An additional 5 people were interviewed of
those who chose not to use Lens, including 3 administrators, 1 computer
scientist and 1 manager.

All of those interviewed are already experienced mail users working
in an environment that has supported mail for over a decade.  All
rely on mail for formal and informal communication.  Their existing
mail system operates in a networked workstation environment.  Users
can create separate windows for composing, reading or browsing through
messages or folders. The Lens prototype was designed to enhance rather
than replace this system; users could chose any or none of the new 
Lens features, as desired.

@skip[1]
@subheading[Method]
@skip[1]

The first interviews were scheduled just after the general electronic
mail announcement of the Lens study.  Several weeks later, Lens was
demonstrated at an open meeting and individuals were again invited to try
it.  Those who chose to participate in the Lens study were interviewed
again, just prior to installing Lens on their machines.  Thus, the data
reported includes one interview for some people and two interviews for
others.

All interviews were scheduled for one hour in the participant's
office.  Everyone was asked to save the day's mail and delete
confidential messages.  The interviewer was able to examine the
participant's mail messages, inbox and mail folders and used this
information to check the participant's perceptions of mail use.

After answering general questions about the Lens study, the interviewer
asked a series of specific as well as open-ended questions.  Participants
were asked to estimate their average numbers of messages sent and
received, mail folders and distribution lists subscribed to.  These
answers were checked against the actual numbers and participants were
asked if the day was typical.  Participants were also asked open-ended
questions about major problems and successes with electronic mail.  They
used this as an opportunity to describe their current communication
patterns, successful mail management strategies, problems that needed to
be addressed and whether or not particular Lens features would be
expected to help.  The actual questions are listed in the appendix.

@skip[1]
@subheading(Three Examples)
@skip[1]

Before examining the overall results of the study, it is instructive
to look at three individual cases.  These cases have been selected to
represent extremes in the use of electronic mail, rather than to
identify "typical" users.  In order to disguise the identities of the
interviewees, their names and some of their personal characteristics
have been changed.

@skip[1]
@subheading(A Classic "Prioritizer")
@skip[1]

Mary is a research scientist with a very active personal network.  She
estimates that she receives over 30 electronic mail messages per day
and receives a large number of telephone calls as well.  Many of these
interactions take the form of personal requests that require her time,
e.g., reviewing papers, serving on program committees, and offering
advice to people at other sites.  Other people have become resigned to
the fact that she will not always answer her electronic mail or return
phone calls; they often find this quite frustrating.

From her perspective, electronic mail is an essential communication
medium that also threatens to dictate her life.  As a result, she
has devised a set of schemes to prioritize her mail, to ensure that
she sees and responds to correspondence that is important to her.  "My
goal is to read as little as possible.  I try not to read mail more
than once a day; I budget my time."  In this case, mail is both part
of the problem and part of the solution.  Because the cost is low for
others to reach her electronically, she is inundated with requests and
it is simply not possible for her to respond to all of them.  She does
not have a secretary or people working for her to whom she can
delegate tasks, so she must prioritize them herself.

She is willing to occasionally miss important messages (assuming,
perhaps, that people will telephone or get to her somehow if it's
@i[really] important).  She has no desire to see unimportant messages.
She identifies several categories of electronic mail.  Priority 0
requires immediate attention.  Priorities 1 and 2 are categorized by
sender and only include messages addressed to her personally.
Priority 3 consists of bulk mailings, which she browses every couple
of months.  She sees mail as a way to maintain her large personal
network of research colleagues and wants help identifying the most
important messages.  She feels as if she is on the edge of losing
control of her mail.

@skip[1]
@subheading(An Overwhelmed "Archiver")
@skip[1]

Ralph is a computer scientist who is responsible for obtaining
information from a wide variety of sources and applying it to specific
problems.  He has hundreds of messages in his inbox and is afraid to
delete them because "there might be something important...What percent
of the ocean don't you like?"  Some of these messages are from
personal friends and require lengthy correspondence, some are requests
for information or other kinds of action, while others contain
information that "may be useful someday", but can't be immediately
categorized.  Many messages require some form of action on his part
and cannot simply be deleted.  His meetings and other work prevent him
from reading mail on a regular basis.  As a result, he often reads
only a fraction of his new messages and reserves the rest for "later".
His inbox is always a jumbled mix of unseen messages, unclassified
messages and messages that remind him to do something.  He is wary of
getting help to do this, because it would increase his feelings of
lack of control.

One of his most pressing problems is trying to organize his messages
in such a way that he can find them again.  "I don't always delete
messages after printing them; they're a reminder in case it gets
lost."  His strategy is to delete clearly unimportant messages,
leaving the rest in his inbox as a reminder of what remains to be
done.  He keeps a large number of different mail folders and transfers
messages into them on an ad hoc basis.  He wants to be able to
automatically identify different characteristics of messages once
they've been acted upon and allow him to use these characteristics to
retrieve messages again.  He also wants some sort of automatic
reminder facility to help him keep track of messages that he still
must process.

In general, he views mail as an absolutely essential communication
medium for both his job and his personal life.  It creates problems
because of the volume of messages (he usually has over 600 messages 
in his inbox and maintains over 40 mail folders), and he feels 
as if the situation is completely out of control.  

@skip[1]
@subheading[A Manager-Secretary Team]
@skip[1]

Ann is a manager who is responsible for a group of researchers.
Unlike the previous users, she does not use mail to maintain a
network of colleagues.  She talks to most of her group face-to-face,
on a regular basis.  Instead, mail is an efficient way to keep
informed about events in the lab, provides a record of interactions,
and is an efficient way to communicate when she is traveling.  "If I'm
on the road, I use mail for almost everything."  

Her primary problem is managing the volume of mail.  Members of her
group copy her on many messages to keep her informed.  She would like
to offload the management of these messages to her secretary.  To be
worthwhile, this delegation process must be faster than doing it
herself.  "I can't afford to spend more than half an hour a day on
mail; it's an inefficient use of my time."

Ann and her secretary have developed a shorthand for exchanging and
processing mail.  Ann flags messages with one of five different
actions for her secretary: "please file", "take some action", "please
reply to", "for your information", and "remind me".  The secretary can
easily prioritize and handle the messages, without going back to Ann
for clarification.  Note that this classification scheme is not based
on the content of the messages, but rather on the actions the manager
chooses to take.  Ann wants help automating this system, to avoid the
redundancy of copying messages back and forth and to save them both
time.

@skip[1]
@subheading[Analysis of the Cases]
@skip[1]

These three users exhibit a striking diversity in their patterns of
mail use.  Not only do they choose to process and organize mail
differently, but they also think about the functions of mail in very
different ways.  Those who want help prioritizing incoming messages
view mail as a time management tool.  Those who want help archiving
messages view it as an information management tool.  Those who see it
as a way to delegate tasks see it as a task management tool.

This level of diversity has been reported in other aspects of work,
including different writing strategies using Notecards, @cite(Trigg),
different desk organization techniques @cite(Malone1), and different
styles of information exchange @cite(Allen1).  While these patterns of
use are diverse, they are not infinitely so.  Individuals tended to
cluster in their views of mail and the kinds of problems it can
address. 

@skip[1]
@subheading[Diversity in Mail Use]
@skip[1]

Table One illustrates the patterns of mail use among those
interviewed.  Users estimated their mail use by examining a single
day's mail and determining whether or not it was typical.  They
estimated average numbers of messages sent and received, average sizes
of mail inboxes, and numbers of distribution lists.  When a range was
given, the midpoint of the range was chosen.  The actual numbers of
mail folders and distribution lists were also recorded.@foot[The mail
system in this organization does not explicitly provide electronic
conferencing, but instead has a very sophisticated distribution list
system.  These lists are "owned" by someone in the organization who
decides whether or not others can add themselves.  Some lists are
mandatory, such as corporate-wide lists.  Others are restricted to
members of a particular group.  Still others are voluntary and include
everything from information for users of prototype software to
non-work-related topics (want ads, political action, local
entertainment, etc.).

When asked to estimate the number of distribution lists, some people
answered verbally (e.g. "few"), others guessed a number, and several
did both.]

Table Two lists the user's estimate of how often mail is read per day and
a rating of the user's feelings of control over mail and the user's
preferences for prioritizing or archiving mail.@foot[Users were asked a
number of other questions, including whether or not they read all of
their mail, how difficult it is to find a message that has been filed,
and how many steps it usually takes.  In addition, users answered
open-ended questions about their mail use.  These have not been included
in the table, but contributed to the interviewer's assessments of the
user's feelings of control and whether they are predominantly
prioritizers or archivers.]  The 18 users in the first three groups,
researchers, computer scientists, and managers, all tried Lens.  The 5
users in the last group, 3 administrators, a computer scientist, and a
manager, did not try Lens.

@skip[1]
@center[Insert Table One about here]

@skip[1]
@subheading[Observations]
@skip[1]

Most users vary somewhat in their estimates of messages they send
(1-10) and receive (12-50) per day.  One user, a senior administrator,
handles significantly more than anyone else.  She sends 30 messages
and receives 75 per day.

Users of this mail system can create mail folders in which to store mail
messages.  Here, the variability among users is much greater, ranging
from 9 to 100 folders.  All job categories show this variability,
indicating that job requirements are not the primary determinant of
number of folders.  

Messages first arrive in a special folder called the inbox.  The sizes
of inboxes vary greatly, ranging from a low of 10 to a high of 1350.
Those with small inboxes often make a point of clearing them out on a
regular basis.  Note that small inboxes are not necessarily correlated
with a low volume of mail.  The administrator with the highest volume
of mail has the smallest average inbox size.  Another administrator
with a low volume of mail has one of the largest inboxes.

Users have very different attitudes towards distribution lists.  First,
nobody has an accurate idea of how many they are subscribed to.
Everybody underestimates the number, probably because it is easy to
forget about low-volume lists.  Second, some users choose to subscribe to
many lists while others remove themselves from as many as possible.
Those in the first category "do not want to miss anything" and are
willing to put up with the extra volume of junk mail.  Four of the six
computer scientists and one researcher placed themselves in this group.
Those in the second category are willing to risk missing mail.  All of
the managers and administrators, most of the researchers (5/9) and one
computer scientist are in this category.  The remaining people feel that
they subscribe to a moderate (and reasonable) number of distribution
lists.

Preferred frequency of reading mail varies considerably.  Two people
are very careful to limit mail reading to once a day, usually for a
specified period of time.  One third of the people in each job group
limit their mail reading to 2-3 times per day.  They allow mail to
accumulate and read it only when convenient.  The rest of the people
read mail as soon as it arrives.  This "constant" reading of mail
refers only to the time people spend at their desks.

The diversity of mail use found in the three examples described earlier
is also apparent in these data.  While message traffic is somewhat
similar, there are large fluctuations in numbers of messages kept in
inboxes and numbers of distribution lists.  The difference between the
lowest and highest value is at least an order of magnitude in all but the
number of messages received.  This variability obtains within job
categories as well as among them.  Note that these items are not
independent of each other.  For example, the number of distribution lists
directly affects the volume of mail actually received.  Other categories
may be correlated because they result from the same cause.  For example,
people who do not like clutter may continuously delete messages from
their inboxes and also maintain a small number of folders.

@skip[1]
@subheading[Does the user manage mail or does mail manage the user?]
@skip[1]

These numbers only tell part of the story, though.  If users' subjective
views of mail are examined, an even greater diversity emerges.  For
example, one person felt that 36 distribution lists was "a few", while
another felt that 20 was "a lot".  One person felt in control with 75
messages a day, while another felt overwhelmed with 23.  What accounts
for this disparity?  This section describes the factors that influence
these feelings of control and hypothesizes about how they relate to
different strategies of work management.

Table Two lists the interviewer's subjective assessment of these
feelings, based on comments made in the open-ended part of the
interviews.  Some people are quite content with mail and feel that
they can use it successfully in their jobs.  Others are "on the edge"
and are barely able to handle their mail.  ("I intend to read all my
mail...someday!")  Still others are out of control ("I am overwhelmed
by mail") and constantly feel that they are missing information and
forgetting to do things because of it.  ("I don't read all my mail.
There's too much.  I sometimes miss meetings and things because I
didn't see the message.")

@skip[1]
@center[Insert Table Two about here]

One indicator of control is how often the user chooses to read mail.
Some feel that mail is seductive and carefully restrict their mail
reading, either by limiting the actual time spent or by restricting
the number of times mail is retrieved per day.  Others treat the
appearance of a "new mail" message as if it were a telephone call; 
they retrieve mail as soon as it arrives.  Those who feel out of control
are often those whose jobs do not require immediate responses to mail
but feel they can't stop themselves from reading it anyway.

The size of the inbox also contributes to feelings of control.  Those
with very small inboxes are far less likely to feel overwhelmed than
those with hundreds of messages.  Most people treat the inbox as a an
on-line "to do" list .  "My inbox also holds unclassified mail.  It
acts as a reminder that something needs to be done".  Not only is it
more difficult to find messages in a large inbox, but the very size
contributes to feelings that there's an overwhelming amount of work
left to be done.

Users have several ways to limit inboxes.  One is to get off voluntary
distribution lists and simply never receive a large number of mail
messages.  Some people are quite willing to do this ("after a while
you get tired of all the junk"), while others are not ("it's worth it
to have to delete 90% if 10% is interesting").  Another way to reduce
inboxes is to systematically delete messages after they've been read
or skimmed.  Some people do this regularly ("I like to prune my mail")
and others let it get out of hand ("If there's a lot of new mail, I do
the easiest thing and don't delete.  So the garbage builds up.")
Several people said that when the inbox gets too big, they copy it to
a mail folder, date the folder, and start over.

Individuals who feel overwhelmed by mail have some or all of the
following characteristics.  They:
@skip[1]
@begin{enumerate,justification off}
Subscribe to many voluntary distribution lists.

Read mail at irregular intervals or constantly.

Try to read all of their mail, but don't always succeed.

Keep hundreds of messages in their inboxes.

Often don't get to the bottom of an inbox. 

Want to save a large percentage of their mail.

Maintain many mail folders on diverse topics.

Have difficulty finding messages.
@end{enumerate}

How can these differences in feelings of control over mail be
accounted for?  First, the role that mail plays in people's work
must be reexamined.  The conventional view, that mail is an
information management system, is not sufficient here.  Two other
dimensions, time management and task management, must also be
considered.  If each is analyzed in turn, it becomes clearer why
different people make the decisions they do to manage their electronic
mail.

Some people who are overwhelmed with information can simply reduce the
number of distribution lists they subscribe to.  One researcher said
"I get off as many distribution lists as possible; then I make friends
with people who filter them!"  However, those whose jobs involve
tracking information cannot simply remove themselves from distribution
lists.  They must actively manage the information that comes in via
mail and archive it in such a way that they can retrieve it when it
becomes relevant.  These users need @i[information management] tools
that effectively identify and classify information.

Mail represents a time management issue for everyone.  If the messages
that appear in the inbox represent tasks to be done, the user must
choose when to perform the tasks.  Those who feel overwhelmed by mail
are often reactive, allowing the order that the messages arrive to
dictate the order that the tasks are performed.  Individuals with jobs
that require immediate responses, such as fixing broken equipment, are
often in this category.  Those who feel in control are more likely to
actively prioritize their mail. A manager may be able to wait days
before replying to most messages.  Many of these users would benefit
from @i[time management] tools that identify critical tasks and help
prioritize them.

Task management is another important issue in feelings of control over
mail.  Some people receive a large number of work requests via mail
and often feel overwhelmed because they have no one to delegate to and
cannot refuse the requests.  Those who feel in control are often those
responsible for delegating tasks in the first place.  Groups of users
need @i[task management] tools that help identify who is most able to
accomplish which tasks and assign them accordingly.

@skip[1]
@subheading[Dimensions of Work Management]
@skip[1]

I have argued that mail contributes to at least three different kinds
of work: information management, time management and task management.
Individuals in this study generally held one or two of these views of
mail, but rarely all three.  These views were revealed when I asked
individuals what kinds of rules they would like to apply to their
mail.  The next three sections will describe these dimensions of work
management in more detail and suggest how mail can successfully assist
with each.

@skip[1]
@subheading[Time Management: Prioritizing New Mail]
@skip[1]

For some people, when the rules are applied is as important as the
content of the rules.  Those who want rules that run @i[before] they
actually read their messages are @b[prioritizers].  They are
interested in identifying important messages, based on any of a number
of criteria, so that they can optimally sequence their work.  These
people are also very interested in rules that result in actions that
do not require their intervention, such as automatically adding a
meeting to an on-line calendar.  They view successful time management
as performing important tasks first and ignoring unimportant tasks.

Prioritizers display some or all of the following characteristics.  They: 
@skip[1]
@begin{enumerate,justification off}
Do not read all of their mail.

Limit the number of times they read mail per day.

Reduce mail volume by getting off distribution lists.
@end[enumerate]

Categorizing people as prioritizers has little to do with how
successful they are at managing their time.  Rather, it relates to
whether or not they view time management as a salient issue in their
current work. As discussed earlier, some prioritizers are quite
successful and others are not, depending on their job responsibilities
and strategies for managing mail.

@skip[1]
@subheading[Information Management:  Archiving Old 
Mail]
@skip[1]

Other users are far more interested in applying rules @i[after]
reading or skimming new messages.  They can be classified as
@b[archivers].  Their jobs often involve discovering, tracking and
filtering large amounts of information.  They do not view eliminating
"unimportant" messages as particularly useful: "I don't trust a
formula for sorting mail before I see it.  I'm afraid it will get
sorted and I'll never look at it again.  I prefer to read it manually
and then have it sort for me."  Because they feel they have to process
everything anyway, they want tools that help them classify interesting
messages.  They also want a consistent scheme for storing messages, to
facilitate later retrieval.  Archivers display some or all of the
following characteristics.  They:
@skip[1]
@begin{enumerate,justification off}
Increase mail volume by subscribing to voluntary distribution lists.

Save a large percent of their mail messages.

Maintain a large number of mail folders.

Tend to read all of their mail, or try to.
@end[enumerate]

Archivers are not simply packrats who are unwilling to delete
information.  They feel that they must view everything at least at a
cursory level, because they must be aware of what is there.  Some
archivers are very organized and have developed efficient filing
systems for their messages.  Richer retrieval mechanisms and faster
access times would be appreciated, but would probably not
fundamentally change their jobs.  Other archivers are very
disorganized and have a difficult time finding anything.  These people
probably need time management help as much as help with archiving.

Prioritizers and archivers are not mutually exclusive, although people
in this study tended to have a preference for one or the other.  An
example of an individual who is both is someone who maintains a large
network of colleagues and also tracks large quantities of information.
Such people would like tools to both help them prioritize their
correspondence and to manage their personal databases of messages.

@skip[1]
@subheading[Task Management:  Requesters and 
Performers]
@skip[1]

Mail can be an efficient medium for delegating tasks.  The burden of
handling these tasks is often distributed disproportionately
throughout the organization.  Some people, particularly managers and
high-level administrators, are more often @b[requesters] of tasks.
Others, usually individual contributors and secretaries, are more
often @b[performers] of tasks.  High level researchers often fit in
both categories, both receiving and delegating requests for action.

Requesters tend to feel less overwhelmed than performers for two
reasons.  First, they receive relatively fewer requests themselves and
second, when they do receive requests, they can often delegate them,
accomplishing work through others.  Performers may feel legitimately
overwhelmed, especially if they cannot refuse requests and have no one
to delegate to.  High level technical people and research scientists
often receive many requests because of their expertise, but because of
their status, can choose which requests to accept.  While they cannot
necessarily delegate their work to others, as those in the first
category can, they can refuse work or request assistance in a way that
those in the second category cannot.

The ease of sending mail messages can increase the kinds of tasks that
are assigned.  From an economic point of view, it should not be
surprising that the effect of lowering the cost of delegating tasks by
mail increases the overall volume of mail.  From the sender's
perspective, the cost/benefit ratio is much improved.  Senders receive
the benefits of a delegated task at a lower cost.  Unfortunately, this
increases the burden on the recipients of these requests who must
perform the tasks.  The overall effect on the organization may be to
improve group productivity.  Even though individuals usually receive
more messages than they send, because one message is sent to one or
more recipients, the lowered cost of assigning tasks may increase the
likelihood that a particular task is performed by the person best
suited to doing it.

By this line of reasoning, groups will benefit from tools that help
distribute tasks throughout an organization.  A number of users in
this study requested special types of messages and rules for this
purpose.  Two managers want to establish routine communication between
themselves and their secretaries.  Another is interested in creating
"organizational processes for handling short-lived groups".  Others
are members of existing groups that handle routine requests from the
outside, mostly bug-fixes and requests for information.  They are
interested in rules that will help them allocate tasks among
themselves.

@skip[1]
@subheading[Implications for the Design of Electronic 
Mail Systems]
@skip[1]

Comments such as "Mail is my lifeblood" indicate the level of
importance of mail in this organization.  Because everyone can be
assured that everyone else has regular access to electronic mail,
these people have adapted mail to support different kinds of work.
Examining these "lead users" of mail @cite[VonHippel] can inform the
design of future mail systems in several ways.  Not only will it help
identify limitations in current mail systems, but it may also
challenge assumptions about the purpose of mail systems and suggest
new approaches that support diverse uses of mail.

The level of diversity found within this small group argues against
searching for a single correct mail strategy.  Instead, it is
important to look for powerful primitives that support the flexible
extension of mail to support different kinds of individual and group
work.  The use of rules to manage mail appears to be such a primitive,
allowing users to modify the rules to meet their individual needs.
It's clear that no single set of rules will be useful for everyone.
However, mail systems that provide the general functionality of rules
are likely to support a greater variety of work.

In this organization, mail is viewed as both part of the problem (it
generates work) and part of the solution (it accomplishes work).
Because the people who feel overwhelmed by mail use it for different
purposes, different solutions must be identified for these users.  The
information management function needs an improved system of
classifying messages.  Semi-structured messages and artificial
intelligence intelligence techniques for abstracting or analyzing
messages may be very useful here.

The time management function needs better ways of identifying
important messages and sequencing them.  These often have less to do
with the content of the messages and more to do with the current state
of the user (e.g. "just back from vacation and facing 300 new
messages" will result in different priorities than "just finished a
big project and finally have time to relax".)

The task management function needs better ways to determine who is
best suited to perform a particular task and assign it accordingly.
"Best suited" must include some indication of the current workload 
of the performer of the task to prevent people from becoming 
overwhelmed.

@skip[1]
@subheading[Conclusions]
@skip[1]

The most striking result of this study is the level of diversity in
patterns of mail use.  Basic mail functions, such as numbers of mail
folders, numbers of distribution lists, and sizes of inboxes, vary by
at least an order of magnitude.  Individuals also vary greatly in
their feelings of control over their mail, ranging from completely in
control to totally overwhelmed.  Much of this diversity can be
explained by the differences in people's work and how that affects
their views of mail.

In this organization, mail has evolved beyond a passive communication
system.  Because everyone can assume that everyone else has access to
mail, mail has become an integral part of everyone's work.  Mail is
both a source of additional work and a tool for managing work.  It
should not be surprising that mail has come to reflect the diversity
found in that work.

Three major forms of work management have been identified: information
management, time management and task management.  Those who view mail
as a time management tool, called @i[prioritizers], are most
interested in identifying and prioritizing important messages.  Those
who view mail as an information management system, called
@i[archivers], are most interested in sorting and retrieving messages.
Those who use mail for task management, called @i[requesters] and
@i[performers], are most interested in assigning tasks to those who
can perform them most efficiently.

Viewing mail as support for different kinds of work can help in the
design of successful mail systems.  An important lesson here is that
an individual designer's own experience with mail is unlikely to
provide sufficient understanding how other people want to use mail.
Mail systems should be designed to accommodate diversity.  Rather than
searching for an optimal set of functions, designers should seek
primitives that provide both power and flexibility.  Mail can be more
than just a communication system: it can be a sophisticated tool for
accomplishing a wide variety of individual and group work.

@skip[1]
@subheading(Appendix)
@skip[1]

Participants were asked the following set of questions:

A.  @ Descriptions of electronic mail use:
@skip[1]

@begin{enumerate,justification off}
How many messages did you send today?

How many messages did you receive today?

Is this a typical day?

How many mail folders do you have?

How many messages are in your inbox?  

Is this typical?

How many distribution lists do you subscribe to?  

How often do you read your mail?

Do you read all of your mail?

What percentage of messages do you wish you had never seen?
@end(enumerate)

B.  @ A subset of the open-ended questions: 
@skip[1]

@begin{enumerate,justification off}
Describe how you use mail.

In what categories do you place your mail messages?  

Can you think of times in the past week in which you needed 
technical information?  What did you do?

Can you think of times in the past month when you've looked 
at a previously filed message?  Describe the procedure you 
used to find it.

What kinds of rules would you like to process your mail?
@end(enumerate)
@skip[1]

@skip[1]
@subheading[Acknowledgements]
@skip[1]

I would like to thank Tom Malone for his extensive comments on early
drafts of the paper and support of the project.  I would also like to
thank Stu Card, Kevin Crowston, Ramana Rao, David Rosenblitt and
Deborah Tatar for their work on the study and insightful ideas.
Finally, I would like to thank Lotte Bailyn, Jintae Lee, Steve
Poltrock, Jane Salk and the participants in the study for their
thoughtful comments and willingness to discuss their different
strategies for managing electronic mail.

@skip[1]
@subheading(References)
@bibliography

