.if n .ls 2
.ds M post
.TM "80-1273-7 80-1274-11" 39199 39199-11
.ND September 30, 1980
.TL
Electronic Mail Without Aliases
.AU "MH 2C-511" 2879
R. Jane Elliott
.AU "MH 2C-572" 6377
Michael Lesk
.OK
UNIX
Electronic mail
.\".so /usr/mel/newCS
.AB
Electronic mail at Bell Labs is usually routed to a system and a user-id.
There are now over 100 BTL UNIX systems connected by the UUCP network,
and it is more and more of a nuisance to remember where your correspondents
log in and what user-id they use.
The new utility
.I \*M
looks up the real names of people in a database of BTL UNIX
users, and sends mail appropriately.
The most specific kind of address is of the form
``ruby.jane.elliott-mh-1273''
but everything except ``elliott'' is optional.
When someone has
no computer address, the mail is routed to a nearby clerk,
with appropriate labels so that the mail need merely be printed
and then put in the company mail.
If the eventual address is not only non-electronic but outside
the company (e.g. at AT&T) the mail is routed to a clerk
near the sender and addressed for the U.S. Mail.
.PP
The names, room numbers, and department numbers of all employees
are updated automatically from the standard company files;
userids can be updated by the users themselves, simply by sending
the appropriate electronic mail.
A line of the form
.DS C
.ft PO
UPDATE: research!mel IS michael.e.lesk-mh-1274
.DE
mailed to
.I \(gapostoffice\(ga!mailroom
.ft 1
will update the appropriate listing.
.PP
As with other data bases, there is the usual choice between
distributing the data base or routing all queries to a single site.
The
.I \*M
command may be used with local directories of users, or all mail
may be sent to a central site which has a phone book and then
the central site can
route and deliver the message.
In addition, it is possible to route some mail locally and then
forward other mail to the central site.
The individual user may also have a directory
of abbreviations;
thus the directory is really a hierarchy of directories
running through personal directories, local site directories,
and finally large central directories.
.AE
.CS 5 0 5 1 0 2
.SH
Introduction
.PP
There are over 100 Bell Labs UNIX systems now in the UUCP network.
It's hard to remember where everyone you know works so that you
can send them electronic mail.
The trend from somewhat meaningful system names
(e.g.
.I mhwpa
or
.I ihuxa)
to meaningless ones
(e.g.
.I alice,
.I eagle,
or
.I groucho)
makes it even more difficult to remember who works where.
As a result, electronic mail is largely used
within single systems, with
only 13% of all mail being to another system.
By contrast, 19% of regular BTL paper mail
goes not just to other groups but to other locations.
.\"this number came from reading mail envelopes, if
.\"anyone ever asks. 15 of 80 addresses changed loc.
..
To make it easier to send electronic mail,
the command
.I \*M
maintains data bases of userids and real names.
It can be used to address electronic mail to people
by their real names.
.PP
We maintain a data base which gives, for all Bell Labs employees,
their real name, department number, location and room number,
UNIX system name, and user-id.
Non-employees can also be entered in the data base if
we wish to send them mail (e.g. AT&T users of BTL computer systems).
The real name, department, and room address of each employee
are taken from the Bell Labs phone book and regularly updated.
We keep a list of UNIX names and user-ids.
We store the data in a B-tree, using Peter Weinberger's programs,
.[
%A P. J. Weinberger
%T UNIX B-trees
%M TM 80-1272-xx
%O To appear.
.]
and can retrieve either the address of a particular individual or
the real name of a computer user.
A smaller data base of clerks is also maintained.  This is a list,
similar to the last, of people with computer addresses who can
be asked to take paper mail and put it in
mailboxes.
.SH
Implementation
.PP
Given a letter and a destination name, the program first
identifies the person in its name list.  If the name is
ambiguous, and the user is at the terminal, a menu of
possible individuals is presented and the user
is asked to choose one.
When the program has identified the addressee, it dispatches the
mail if possible.  Several routes are available:
.IP 1.
If the addressee has an electronic mail address, the mail is
sent electronically.
.IP 2.
If the addressee is at Bell Labs but has no login user-id, the
mail is formatted for paper and sent electronically to
the closest clerk to the addressee.  ``Closest'' is defined
by the organization number; i.e. same department if possible,
otherwise same laboratory if possible, otherwise same division.
If no clerk is registered anywhere in that organization,
then the program selects a clerk at that main location.
.IP 3.
If the addressee is not at Bell Labs, but the sender is, the
mail is formatted for paper and sent electronically to the
closest clerk to the sender.  This clerk then puts the letter
in the external mail.
.IP 4.
If we have no electronic address for the addressee, and neither
the addressee nor the sender is at Bell Labs, then at present
we abandon the mail.  There is no reason in principle not to
have a list of clerks outside BTL, at least at Western and AT&T,
but at the moment we have decided not to keep such a list.
.LP
In any case, the mail is identified as to the sender: we look up
the user invoking the command in our data base, and supply his
real name and department in the mail.
The pattern of operation is shown in the figure below.
The mail moves electronically until it reaches either
the final destination or the clerk.
If the destination is at BTL, the clerk is near the
recipient; otherwise the clerk is near the
sender.
.PS
 box "sender"
arrow
Box1:
 box "mailroom" "computer"
arrow up from Box1.n
 box "phone" "book"
arrow down from Box1.s
 box "user" "list"
move to Box1
move right
move right
{
move up
Box4:
box "target" "system"
}
{
move down
Box5:
box "nearby" "clerk"
}
move right
move right
Box6:
 box "recipient"
arrow from Box1.e to Box4.sw
arrow from Box1.e to Box5.nw
arrow from Box4.se to Box6.w "electronic " rjust
arrow from Box5.ne to Box6.w "paper " rjust
.PE
.PP
Clearly,
.I \*M
can only be used to communicate with sites in
.I uucp
communication with the mailroom computer.
We hope that some administrative solution, perhaps similar to the
one proposed by Grampp, Koenig, and Ritchie,
.[
%A F. T. Grampp
%A A. R. Koenig
%A D. M. Ritchie
%T Directory assistance for UUCP
%M MF 3644-800318.01
%D March 18, 1980
.]
will provide for general updating of
.I uucp
lists.
In any case keeping these mail lists up to date on
one computer is less work than keeping them up to date
everywhere.
.SH
Usage
.PP
The
.I \*M
command is used just as the regular
.I mail
command is used.
There is no difference at all if you intend to
read mail, since
.I \*M
invoked without arguments just executes
ordinary
.I mail.
If the user has a shell environment parameter MAILP set, it
provides the name of the mail program; otherwise ``mail''
is used.
This permits a user who prefers Berkeley mail or other mail
variants to have it invoked instead of the standard mail command.
To send mail, you type
.I
\*M addressee1 addressee2 ...
.R
and supply the message on the standard input.
The usual
.I -R
option is also recognized (this specifies ``return receipt requested''
to give positive confirmation that the mail has been received and read).
The format for addressee is
.I firstname.middle.lastname-location-department
in which everything but the last name is optional.
Upper and lower case letters are equivalent throughout, and
the location and department may be in either order.
Location should be specified as the ordinary Bell Labs
2-letter code;
AT&T building numbers are not recognized.
The first name, middle name, and department may be searched as
prefixes, i.e. initials will match names and as many digits
of the department number as are known may be used.
.PP
To update your listing, send mail to
``\(gapostoffice\(ga!mailroom''
of the form
.DS C
.ft PO
UPDATE: system!userid IS john.a.smith-ho-3456
.DE
where 3456 is the department number.
This produces a listing in the directory as indicated,
changing the previous one if one existed.
The Bell Labs location and room number are obtained from
the standard Bell Labs telephone book data and are not
supplied by the user.
To register a U.S. mail address only, and not
a computer address, send
.DS C
.ft PO
UPDATE: john.smith USADDR WECo.; 220 Broadway; New York 10007
.DE
Sometimes, it may be desirable to define a particular userid,
but not to direct mail there.  It may, for example, be a secondary
userid for the user in question; or, although primary, it may be
a userid for someone who rarely uses the computer.
It is nevertheless useful for
.I \*M
to know who owns the userid, so that it can identify mail sent
from that userid.  To indicate ownership of a userid without
getting mail sent to it, send
.DS C
.ft PO
UPDATE: system!userid ANOTHER john.smith
.DE
to the same place
(\(gapostoffice\(ga!mailroom).
To simply delete a listing, without replacing it,
send mail of the form
.DS C
.ft PO
UPDATE: system!userid WAS john.a.smith-ho-3456
.DE
to the usual place.
Changes in room number or location are picked up automatically from
the Bell Labs telephone directory and need not be sent in.
We hope that cooperating systems will, perhaps once a week, send
in a current list of their users so that people will not need to
send their own change of address forms.
To aid in system administration, there is another update
command
.ft PO
NEWPASSWD
.ft 1
which is used in the normal way, i.e.
.DS
.ft PO
UPDATE: system!userid NEWPASSWD john.a.smith-ho-3456
.DE
and is taken to mean ``IS'' if the userid does not already appear
in the lists and ``ANOTHER'' if it does.  This is thus
an appropriate command when a new password file is received
from a remote site and all the names in it, old and new, are to
be fed to the updating program.
.PP
There are two ways this command can be made available on other systems.
First, the data bases could be distributed.
Although perfectly feasible, this involves distributing
about 1,200,000 bytes of information.
Secondly, a site can define
.I \*M
as
.DS C
.ft PO
uux - "\(gapostoffice\(ga!\*M -u (`uname -n`!`logname`) $*"
.DE
where
.I uname
and
.I logname
are the standard USG commands which print, respectively, the system
name and the user name.  Systems deriving from Research versions
will need to replace
.I \(gauname\(ga
by the explicit name of the system and
.I logname
by the equivalent command, which is named
.I getuid.
This will invoke
.I \*M
remotely via
.I uux;
the mailroom system will then process the mail and forward it.
In this case, diagnostics are returned when
a direct invocation of the program would have resulted
in a choice of several names.
.PP
We have specified the name of the mailroom computer through
a
.I postoffice
command which prints its name.
At present the appropriate name
is
.I alice
and the
.I postoffice
command should just be
.I "echo alice"
or any equivalent.
In the future the ``mailroom'' computer may be moved to
a different site, depending on administrative decisions.
Several sites might be used, particularly if it is desired
to take advantage of local area networks
in some locations.
Another reason for using several sites might be
to permit security-sensitive sites to avoid having
to join even the UUCP public network and yet exchange
mail among themselves.
In either case, the data bases would have to be distributed,
possibly with deletions for security reasons.
.SH
Local and Personal Lists
.PP
To avoid typing of long addresses, and to facilitate the
maintenance of mailing lists,
.I \*M
permits users to maintain their own lists of abbreviations.
All names are first looked for in a file
.I $HOME/lib/mail.aliases
where
.I $HOME
is the invoker's login directory.
This file, if it exists, should contain lines like
.DS
jane	elliott-127
sandy	a.g.fraser-mh
steve	s.c.johnson-1273
\&\s+2.\|.\|.\s0
1273	jane sandy steve  \s+2.\|.\|.\s0
.DE
and can be used either for giving mailing lists or expanding
abbreviations.
If an address matches the first word on any line,
mail is sent to the names that follow on the line.
The following names must either be in normal
.I \*M
addressee format,
or must be ordinary
.I system!userid
names (discouraged, since it requires you to do your own list maintenance),
or must be defined elsewhere
in the file.
Infinite loops of definitions are rejected (infinite
is defined as five or greater).
The entire local directory system requires, of course, that you actually
have a copy of
.I \*M
on your system, and not merely
the
.I uux
command to execute on a remote postoffice.
.PP
When
.I \*M
is unable to find a name in its telephone book,
it can forward the request to another system.
We imagine that systems are likely to maintain a database of their
own users.
This prevents local messages from requiring
a remote call (the time
for
.I uucp
between systems is 2 minutes or so).
The non-local mail can still be forwarded to
a central site.
If this is desired, the local site must have its own
copy of the
.I \*M
command, installed as such, and must have
the
.I uux
line given above as a command
.I genpost.
The
.I genpost
command will be invoked by
.I \*M
for the names it can not handle locally.
.PP
At present, we envisage one central Bell Laboratories directory.
However, if some group of systems is connected by a hardwired network,
and wishes to speed up service, they may want to have a copy of the
full directory.
For example, it may be reasonable to provide another postoffice system
at Indian Hill.
It is also possible, if this system spreads to Bell System
computers outside BTL, that there should
be a master list of all participating UNIX
systems and their users,
to permit company to company electronic mail.
The disadvantage of this hierarchical arrangement, of course,
is that it delays the error message on ordinary misspellings
of names.
Some experience will be necessary to
decide how best to arrange matters.
.SH
Future Plans
.PP
Conceivably, traffic may get so large that we will be forced to dedicate
a computer system to electronic mail.
An average mail message to a remote site takes 6.8 seconds of
11/70 CPU time (all but about 1 second is in ordinary mail).
Although this could be reduced somewhat by avoiding as many
process invocations as now occur,
even so it seems there is a capacity for thousands of
remote messages per day, which seems adequate for a long time.
The mail traffic from people on our system, for example, is around 140 messages
sent per day, of which 30 go to remote sites.
.PP
A dedicated machine could be rather small; it would need only perhaps
a 5Mbyte disk, and all of the mail programs fit in
about 30K address space.
However, note that a large number of ACUs would be desirable;
consider, for example, the 11/70, which takes 7 CPU seconds per call
of 2 minutes real time each.
This implies about 18 calls at a time, and if half are
outgoing a need for 9 ACUs.
An 11/23, which is much slower, might need perhaps 3 ACUs.
.PP
In the event that special hardware is dedicated to
electronic mail, it may be necessary to charge
separately in order to recover the costs.
We thus envisage the eventual design and sale of UNIX stamps,
to be used for electronic postage.  However, following the
example of the Trucial States and San Marino, we see no reason
why these could not be sold to collectors, thus turning a net profit.
.SH
Acknowledgment
.PP
The help and encouragement of A. G. Fraser is gratefully acknowledged;
also, the suggestions of R. F. Rosin have been most valuable.
.SG