                               Background Details

Domain Names

   Domain names are used to uniquely name each host on the Internet. A
   domain name has a number of parts separated by periods. Each label
   represents a level in the hierarchy. An example of a name is:

     olive.cac.washington.edu

   In this domain name the top-level label is edu, indicating it is at an
   educational institution, the second-level label is washington,
   indicating the University of Washington. cac is a specific department
   within the University of Washington, and olive is the host name. The
   top-level names are assigned by Internet organizations, and other names
   are assigned at the appropriate level. The Domain Name Service, DNS, is
   the distributed database used to look up these names.

   Pine relies on domain names in multiple places. A domain name is
   embedded into the message-id line generated for each piece of email. A
   domain name is needed to contact an IMAP server to get access to remote
   INBOXes and folders. Most importantly, domain names are needed to
   construct the From: line of your outgoing messages so that people on
   the Internet will be able to get email back to you.

   On UNIX systems, you can set the domain via the user-domain variable in
   the Pine configuration file, or rely on the file /etc/hosts which
   usually sets the name of the local host. While Pine can often deliver
   email without the domain name being properly configured, it is best to
   have this set correctly. Problems can usually be solved by adjusting
   the system's entry in the /etc/hosts file. The fully-qualified name
   should be listed before any abbreviations.

     128.95.112.99 olive.cac.washington.edu olive

   is preferred over

     128.95.112.99 olive olive.cac.washington.edu

   On PCs, the task of configuring the domain name is a bit different.
   Often times, PCs do not have domain names-they have IP addresses. IP
   addresses are the numbers which uniquely identify a computer on the
   network. The way you configure your IP address depends on the
   networking software which you use on the PC. You can refer to the
   documentation which came with your networking software or see the PC
   specific installation notes for help configuring the IP address with
   your network software.

   With PCs, it is vital that users set the variable user-domain in the
   Pine configuration file (PINERC).

   Details on configuring Pine with correct domain names can be found in
   the Domain Settings section of this document.
     __________________________________________________________________

RFC 822 Compliance

   Pine tries to adhere to RFC 822 a little more strongly than some other
   mailers and uses the "full name <address>" format rather than the older
   "address (full name)" format. The intent of the standard is that
   parentheses should only be for comments. Pine displays and generates
   the newer format, but will parse the old format and attempt to turn it
   into the new one.

   As far as outgoing email is concerned, Pine fully-qualifies addresses
   whenever possible. They are even displayed in fully-qualified form on
   the terminal as the user composes a message. This makes addresses more
   clear and gives a hint to the user that the network extends beyond the
   local organization. Pine implements fully-qualified domain names by
   tacking on the local domain to all unqualified addresses which a user
   types in. Any address which does not contain an "@" is considered
   unqualified.

   The newer format for addresses allows for spaces and special characters
   in the full name of an address. For this reason, commas are required to
   separate addresses. If any special characters as defined in RFC 822
   appear in the full name, quotes are required around the address. Pine
   will insert the quotes automatically. The common cases where this
   happens are with periods after initials and parentheses.

   Because Pine fully complies with RFC 822, it is sometimes difficult to
   use non-Internet address formats such as UUCP's host!user or DECNet's
   USER::HOST with Pine. People who run Pine on these systems have made
   local modifications to Pine or to the mail transport agent (e.g.
   sendmail) to make things work for them.

   Pine expects dates to be in the standard RFC 822 format which is
   something like:
        [www, ] dd mmm yy hh:mm[:ss] [timezone]

   It will attempt to parse dates that are not in this format. When an
   unparsable date is encountered it is displayed as xxx xx when shown in
   the FOLDER INDEX screen.
     __________________________________________________________________

SMTP and Sendmail

   Pine is a user agent not a message transfer agent. In plain English,
   that means Pine does not know how to interact with other computers on
   the Internet to deliver or receive email. What Pine does know how to do
   is help users read, organize and create email. The "dirty work" of
   delivering and accepting email is handled by other programs.

   All outgoing email is delivered to a mail transfer program or to an
   SMTP server. The most common mail transfer program is sendmail.

   Pine 3.91 and earlier:
          When Pine on a UNIX computer uses the local sendmail, it first
          writes the message to a temporary file in /tmp. Then Pine runs a
          shell in the background that runs sendmail on the temporary file
          and then removes it. This is done with a shell in the background
          so the user doesn't have to wait for sendmail to finish. By
          default, sendmail is invoked with the -t flag to cause it to
          read and parse the header to determine the recipients; the -oem
          flag to cause errors to be mailed back; and the -oi flag to
          ignore dots in incoming messages. Systems administrators can
          choose to configure Pine to use a different mail transfer
          program or even sendmail with different flags. See the section
          on UNIX Pine Compile-time Options for more details on this.

          Pine can also operate as an SMTP client. SMTP stands for Simple
          Mail Transfer Protocol; it specifies the rules by which
          computers on the Internet pass email to one another. In this
          case, Pine passes outgoing email messages to a designated SMTP
          server instead of to a mail transfer program on the local
          machine. A program on the server then takes care of delivering
          the message. To make Pine operate as an SMTP client, the
          smtp-server variable must be set to the IP address or host name
          of the SMTP server within your organization. This variable
          accepts a comma separated list of servers, so you can specify
          multiple SMTP servers. PC-Pine only runs as an SMTP client.

   Pine 3.92 and later:
          The selection of which MTA to use depends on the settings of
          sendmail-path, smtp-server, and compile-time options. The first
          MTA specified in the following list is used:

         1. sendmail-path in /etc/pine.conf.fixed
         2. smtp-server in /usr/local/pine.conf.fixed
         3. sendmail-path specified on the command line.
         4. smtp-server specified on the command line.
         5. sendmail-path in the user's .pinerc file.
         6. smtp-server in the user's .pinerc file.
         7. sendmail-path in /etc/pine.conf
         8. smtp-server in /usr/local/pine.conf
         9. DF_SENDMAIL_PATH defined at compile time.
        10. SENDMAIL and SENDMAILFLAGS defined at compile time.

          If the sendmail-path form is used, a child process is forked,
          and the specified command is executed with the message passed on
          standard input. Standard output is then passed back and
          displayed for the user. NOTE: The program MUST read the message
          to be posted on standard input, AND operate in the style of
          sendmail's "-t" option.

          If an smtp-server is specified, a connection to the server is
          opened. If the message contains 8-bit text, ESMTP 8BITMIME
          negotiation is attempted. The message is then sent using SMTP
          commands.

          If none of the above are set, the default sendmail program is
          invoked with the "-bs -odb -oem" flags, ESMTP negotiation is
          attempted, and the message is sent.
     __________________________________________________________________

Internet Message Access Protocol (IMAP)

   IMAP is a remote access protocol for message stores. Pine uses IMAP to
   get at messages and folders which reside on remote machines. With IMAP,
   all messages are kept on the server. An IMAP client (such as Pine) can
   request specific messages, headers, message structures, etc. The client
   can also issue commands which delete messages from folders on the
   server. IMAP's closest kin is POP, the Post Office Protocol, which
   works by transferring an entire mailbox to the client where all the
   mail is kept. For a comparison of IMAP and POP, see the paper
   "Comparing Two Approaches to Remote Mailbox Access: IMAP vs. POP" by
   Terry Gray. A more detailed exploration of message access may be found
   in the paper " Message Access Paradigms and Protocols." These papers
   may be found in the /mail directory of the anonymous FTP server at
   ftp.cac.washington.edu.

   IMAP Features:
     * Allows access to mail folders from more than one client computer.
     * Works well over low-bandwidth lines because information is sent in
       small pieces as needed by the user. For example, only header
       information is sent to build index lists, and if someone sends a
       2MB audio file via MIME, you can choose when (or if) you want to
       get that part of the message.
     * Email can be delivered and stored on a well-maintained and reliable
       server which is "always-up".
     * Folders can be accessed and manipulated from anywhere on the
       Internet.
     * Users can get to messages stored in different folders within the
       same Pine session.
     * Allows use of IMAP server for searching and parsing.
     * The latest revision of IMAP (IMAP4) also provides for disconnected
       operation, including resynchronization of message state between
       mail servers and message caches on clients. Pine does not yet
       support this capability, however.

   IMAP2 is defined in RFC 1176. IMAP4rev1, the revision to IMAP2, is
   described in RFC 3501. Further information about IMAP may be obtained
   from the University of Washington's IMAP Information Center on the
   World Wide Web.

   Pine 4.00 is an IMAP4rev1 client.
     __________________________________________________________________

Multipurpose Internet Mail Extensions (MIME)

   MIME is a way of encoding a multipart message structure into a standard
   Internet email message. The parts may be nested and may be of seven
   different types: Text, Audio, Image, Video, Message, Application and
   Multipart (nested). The MIME specification allows email programs such
   as Pine to reliably and simply exchange binary data (images,
   spreadsheets, etc.). MIME includes support for international character
   sets, tagging each part of a message with the character set it is
   written in, and providing 7-bit encoding of 8-bit character sets. It
   also provides a simple rich text format for marking text as bold,
   underlined, and so on. There is a mechanism for splitting messages into
   multiple parts and reassembling them at the receiving end.

   The MIME standard was officially published in June of 1992 as RFC 1341
   and subsequently revised in RFC 2045 when it became a full Internet
   Standard. Pine 3.0 was one of the first email programs to Implement
   MIME. Now, there are dozens of commercial and freely available
   MIME-capable email programs. In addition, MIME is being added to
   newsreaders so MIME messages can be posted and read in USENET
   newsgroups.

   The MIME standard also includes support for non-ASCII text in message
   headers through the extensions described in RFC 1342 and subsequently
   revised in RFC 2047. Support for RFC 2047 was added in Pine 3.92.

   An actual MIME message looks something like this:
Date: Tue, 12 Mar 1996 15:39:35 -0800 (PST)
From: David L Miller <dlm@cac.washington.edu>
To: David L Miller <dlm@cac.washington.edu>
Subject: =?iso-8859-1?Q?Test_MIME_message_with_RFC-1522_headers_=28=E1?=    =?is
o-8859-1?Q?=E2=E3=29?=
Message-Id: <Pine.ULT.3.92.960312150851.21583I-101000@shiva2.cac.washington.edu>
Mime-Version: 1.0
Content-Type: MULTIPART/MIXED; BOUNDARY="0-1737669234-826673975=:21583"
Content-Id: <Pine.ULT.3.92.960312153928.21583O@shiva2.cac.washington.edu>

  This message is in MIME format.  The first part should be readable text,
  while the remaining parts are likely unreadable without MIME-aware tools.
  Send mail to mime@docserver.cac.washington.edu for more info.

--0-1737669234-826673975=:21583
Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
Content-ID: <Pine.ULT.3.92.960312153104.21583L@shiva2.cac.washington.edu>

The text of the message would go here. It is readable if
one doesn't mind wading around a little bit of the MIME
formatting. After this is a binary file in base 64
encoding.

|\ |  |\/|  David L. Miller    dlm@cac.washington.edu  (206) 685-6240
|/ |_ |  |  Software Engineer, Pine Development Team   (206) 685-4045 (FAX)
University of Washington, Networks & Distributed Computing, JE-20
4545 15th Ave NE, Seattle WA 98105, USA

--0-1737669234-826673975=:21583
Content-Type: APPLICATION/ZIP; NAME="test.zip"
Content-Transfer-Encoding: BASE64
Content-ID: <Pine.ULT.3.92.960312153638.21583N@shiva2.cac.washington.edu>
Content-Description: Test Attachment

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--0-1737669234-826673975=:21583--


   For details about Pine's implementation of MIME, see the two MIME
   sections "MIME: Reading a Message" and "MIME: Sending a Message" later
   in this document.
     __________________________________________________________________

Folder Collections

   Folder Collections are Pine's way of dealing with more than a single
   group of folders. With advent of PC-Pine and the development of tools
   within IMAP to better manage remote folders, the time was ripe to
   provide a mechanism for defining a group of remote folders. PC-Pine
   forced the issue in that many potential PC-Pine users would be
   migrating from UNIX Pine in a time-sharing environment and, thus, would
   have some investment in their archived messages on that host.

   For a more complete description of Folder Collections, see the section
   on "Syntax for Collections."

   The Pine distribution is designed to require as little configuration
   and effort at compile time as possible. Still, there are some Pine
   behaviors which are set at the time you compile Pine. For each of
   these, there is a reasonable (our opinion) default built into the code,
   so most systems administrators will have no need for these steps.
