    Network Working Group                                         D. Crocker  (ISI)
    Request for Comments: 720                                              Aug 1976
    NIC #36337
    References: RFC #680

              Address Specification Syntax for Network Mail

    Experience with processing mail on the Arpanet has pointed up many
    addressing issues, including:

    1. People's names are not the same as their addresses;

    2. Mailing lists can get quite long;

    3. To allow responding, messages often need to carry all of their
    mailing list with them;

    4. It would be very useful to be able to send mail to files other
    than the person's primary mailbox.

    The current mail syntax, specified in RFC 680, does not provide a
    convenient mechanism for distinguishing between a person's name and
    their mailing address. In cases of shared directories, the ATTN: clause
    is marginally adequate; however it is completely inappropriate for
    single-user mailboxes in which the address specification is simply
    cryptic. CMU's identification tags are good examples of this problem,
    since they tend to appear to be random character sequences; the use of
    initials as tags also points up the problem. If you doubt the
    referential ambiguity of addresses, then try to use only the information
    presented, rather than random personal knowledge, to discern who
    Micro@ISI, JFH@ISI, or Greep@ISD are. By having a formal syntax for
    separately specifying names and addresses, mail display software can
    printout out name lists which only contain human names...makes things
    friendlier.

    The problem with long mailing lists is that, if included in the text of
    a message, they often are longer than the main part of the message.
    Group names are allowed in address fields primarily to circumvent this
    problem. However the advent of semi-automated message answering, in
    which a receiver's message system prepares address lists for reply
    messages by copying appropriate fields from the original message, makes
    the current mechanism deficient: having the group name means that the
    receiver does not have the names/addresses of the members of the group.
    A convention is generally followed, now, which has the group name be a
    pathname to the file containing the list. Though facilitative, this
    does not represent an adequate solution.

    And lastly is the issue of multiple mailboxes for a single user. This
    feature is probably has the largest potential for teleconferencing
    applications, with messages for an on-going discussion automatically
    placed into a separate mailbox. In the case of shared directories, this
    mechanism also would allow easy channeling into each person's own
    mailbox.

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    With these needs in mind, and until a more robust mail syntax and
    protocol is specified, the following general syntax is proposed to
    augment the existing syntax specified in RFC 680, for address fields
    specified by the user:

    Name:(Person(User-Id(Mailbox) at Host),...),; ...

    Where

    "Name" is the name of the mailing list; "Person" presumably is
    the name of the person receiving the mail;

    "User-Id" is their online reference name (usually their signon
    directory);

    "Mailbox" is a a secondary mailbox/file;

    and the rest conforms to RFC 680, although "@" may be used in
    place of " at " in the specification.

    Parentheses may be replaced by other bracketing pairs ([], {}, <>).
    Quotation marks must be used any time the string contains ambiquating
    characters, such as space or parentheses. The brackets after Name are
    used to request exclusion of the address list from the message, instead
    using text which gives the pathname to the source of the list.

    The formal syntax for address specification, within network mail
    actually sent, is included in the next section.

    Not all of a specification is required, so perhaps some examples will
    clarify things:.

    A normal specification, as used currently: Walker at ISI

    A named list, to be carried with the message, with the last
    address not a member of the list: List:Walker at
    ISI,greep@rand-isd;Action@ISI

    A named list, NOT to be carried with the message; the list
    contents will be replaced with a text string indicating the source

    of the list -- not very useful if the list is typed in by the
    user, rather than pulled from a file; therefore
    List:(Walker@ISI,greep at rand); Action at ISi will be changed to
    appear in the message as List:("/rnd/dcrocker/mail.list"); Action
    at ISI

    A list with personal names. separate from addresses: "Steve
    Walker"[Walker at ISI], Bob<rha@isd>

    A teleconferencing address list:
    Talkers:"Dave C"(DCrocker(TC.msg)@isi),...;

                                      -2-

    Formal Specification
    --------------------

    The following modified BNF is to serve as a direct
    addition/replacement for specifications within RFC 680. The fields
    eliminated from the existing specification are: <addressee item>,
    <address list>, <addressee>, <mailbox>, <host spec>, <attention spec>.
    <user list>, <mailbox group>, <group numbers>, and <mailbox list>.

    <Attention spec> can be performed through use of the person's name
    and secondary file specification. Also, <Sender> should be modified
    to be::

    Sender = "SENDER: " Individual

    And the added fields are:

    Address-Field = Address-List / Address-List ,,:,
    Address-Field

    Address-List = Individual-List / Group-List

    Group-List = Group-Name Group-Members

    Group-Name = / Name ":"

    Group-Members = Individual-List / L-Bracket Pathname
    R-Bracket

    Pathname = {A Name which can at least provide a
    human with enough information to find
    the file containing the Group-List}

    Individual-List = Individual / Individual
    Individual-List
    Address Specification Syntax for Network Mail

    Individual = Mailbox / Name L-Bracket Mailbox
    R-Bracket

    L-Bracket = "(" / "[" / "{" / "<"

    R-Bracket = ")" / "]" / "}" / ">"

    Mailbox = Id Secondary-File At Host

    Id = Name

    At = "" at "" / "@"

    Host = {An acceptable host name}

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    Secondary-File = / L-Bracket Filename R-Bracket

    Filename = Name

    Name = {An Ascii string without carriage
    return, line feed, space, '"', ",",
    ";", or any L-Bracket or R-Bracket} /
    '"' {An Ascii string with any double
    quotation marks doubled} '"'

    The particular L-Bracket and R-Bracket characters used must match
    each other. The requirement for quotation marks has been made more
    severe than absolutely necessary in order to simplify software
    requirments. Note also that the above specified syntax is for
    inter-entity communications and is not necessarily indicative of what
    the user types.

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