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comp.mail.mime FAQ, part 1 of 3 (frequently asked questions list)


Archive-Name: mail/mime-faq/part1
Version: $Id: mime1,v 3.15 1996/01/02 00:00:25 jsweet Rel $
Posting-Frequency: monthly


==========================================================
comp.mail.mime frequently asked questions list (FAQ) (1/3)
==========================================================
Part 1: Answers to Frequently Asked Questions about MIME
--

Overview
--------
This is part 1 of a Frequently Asked Questions document about MIME, the
multipurpose and multi-media standard for Internet mail.

Part 1 covers frequently asked questions.

Part 2 is a listing of MIME products.

Part 3 covers advanced topics.

Sections in the table of contents that have changed since the last
posting are marked with a '!' in the first column.  New sections are
marked with '+'.

Contents
--------
Part 1: Answers to Frequently Asked Questions about MIME (this file)
========================================================
  1)     Introduction
  1.1)   Authorship
  1.2)   Conventions
  1.3)   Where can I get the comp.mail.mime FAQ?

  2)     What is MIME?
  2.1)   Introduction
  2.2)   MIME features that may or may not be present
! 2.3)   Help!  I got a message in MIME format--how do I decode it?
  2.4)   Further information
  2.5)   MIME glossary
! 2.6)   Newsgroups and mailing lists
  
  3)     Miscellaneous questions
  3.1)   What can I use to display MIME messages?
  3.2)   What's "text/enriched"?
! 3.3)   What about security issues?
  3.4)   So, does MIME introduce any new security problems?
! 3.5)   What about a group 3 facsimile encoding?
  3.6)   Should I always use external body parts to save space?
  3.7)   What mail servers can I reference?
  3.8)   Can I interwork between MIME and X.400?
  3.9)   Why does MIME define base64 instead of using uuencode?
  3.10)  How can I use uuencode with MIME?
+ 3.11)  Does Microsoft Mail support MIME?
+ 3.12)  Can I do MIME on a (pick one) PC/Macintosh/Envoy/Whatever?

  4)     MIME information available from the Internet
  4.1)   Anonymous FTP
  4.2)   Mail-based archive servers
  4.3)   Gopher
  4.4)   World Wide Web
  
  5)     Published books and articles
  
  6)     MIME based relays for commercial mail services
! 6.1)   Large national or international providers
  6.1.1) ATTMAIL
  6.1.2) CompuServe
  6.1.3) RadioMail
  6.2)   Local and regional providers

Part 2: MIME products (posted separately)
=====================
! 7)     Freely available MIME packages
  7.1)   Libraries and Patches
  7.2)   Conversion tools and extension packages
! 7.3)   Mail user agents and transport systems

! 8)     Commercial MIME packages

  9)     Packages for MIME in USENET
! 9.1)   Introduction
  9.2)   News readers and transports with MIME support

Part 3: Advanced topics (posted separately)
=======================
  10)    Information
! 10.1)  MIME-relevant RFCs and other standards
  10.2)  MIME types
! 10.2.1)  List of registered MIME types
! 10.2.2)  List of known unregistered MIME types
  10.3)  Internet Engineering Task Force (IETF) working groups

  11)    Developers' FAQs
  11.1)  How can I register a new MIME type?
  11.2)  What's ESMTP, and how does it affect MIME?
  11.3)  Where can I get some sample MIME messages?
  11.4)  Wouldn't MIME be better if it did <foo>?
  11.5)  So what about multilevel encodings?
  11.6)  Why doesn't MIME include a mechanism for compression?
  11.7)  What's this Content-Disposition header?

  12)    Acknowledgements
  13)    Permissions
--

1) Introduction
---------------

1.1) Authorship

Current maintainer:
  Jerry Sweet <mime-faq@ics.uci.edu>

Previous maintainers (thanks, guys!):
  Ed Vielmetti - originator
  Tim Goodwin

Contributions have come from a cast of dozens; see section 12 for the
list of contributors.

--------------------------------

1.2) Conventions

 - Direct quotations begin with an attribution in a standard format,
   and are indented by four spaces.
 
 
 - Pointers to resources available via the Internet, such as references
   to FTPable goodies, appear in WWW URL format.  URLs beginning with
   "ftp:" refer to FTP sites.  For example:
 
   ftp://domain.name/path/to/package
 
   Those with FTP access, but without WWW access, may treat such
   references as follows:
 
   1. Log into host domain.name using anonymous FTP
   2. Look for /path/to/package
 
   An FTP reference usually lists only the distribution site; please
   try your nearest FTP archive first.  Archie may be of some help
   here.
 
   URLs beginning with "http:" refer to WWW servers.  URLs beginning
   with "gopher:" refer to gopher servers.
 
   Internet browsing tools, such as Mosaic, know about URLs.
 
 
 - You'll occasionally see text in braces, like this.
 
   { Here is some example meta-text. }
 
   Sometimes, this indicates a place where information is missing, or
   where the information may be unreliable, or where major changes are
   planned in the near future.  You can ignore these if you're just
   looking for information.  But if you can help fill in the gaps, and
   you want to achieve fame, fortune, and your name at the bottom of
   this FAQ, please send e-mail to the maintainer.

--------------------------------

1.3) Where can I get the comp.mail.mime FAQ?

 - It is posted approximately monthly to the newsgroups comp.mail.mime,
   comp.answers, and news.answers.  The "Expires:" field is set such
   that---on systems that honor this field---the most recent edition
   will always be in the news article database.
 
 
 - Many sites archive news.answers postings, including these:
   
   ftp://ftp.uu.net/usenet/news.answers/mail/mime-faq/
   ftp://rtfm.mit.edu/pub/usenet-by-group/news.answers/mail/mime-faq/
   
   If possible, please try to find a closer site; for example, by
   asking archie for "mime-faq".
   
 
 - HTML versions of the MIME FAQ are available at these URLs:
 
   http://www.cis.ohio-state.edu/text/faq/usenet/mail/mime-faq/top.html
        (Brought to you by Ohio State University, USA.)

   http://www.cs.ruu.nl/wais/html/na-dir/mail/mime-faq/.html
        (Brought to you by the Department of Computer Science, 
         Utrecht University, The Netherlands.)
 
   If you find a non-working hypertext link in the HTML versions,
   you're welcome to bring it to the attention of the MIME FAQ
   maintainer, but unless it's a problem with a URL reference in the
   original document, the MIME FAQ maintainer probably can't fix it
   directly.

   ***In particular, RFC references in the Ohio State version may still
   point to pages saying "they've been moved".  This is beyond the 
   control of the MIME FAQ maintainer.***

 
 - If you are reading this FAQ via some fixed medium such as hardcopy
   or CD-ROM, please try to obtain the latest edition from the net
   instead.


There is also a Part 0, the "Meta-FAQ", posted monthly, that attempts
to help with any special problems that you may have with reading MIME
messages, such as this one.

--


2) What is MIME?
----------------

2.1) Introduction
  
MIME, the Multi-purpose Internet Mail Extensions, is a freely available
specification that offers a way to interchange text in languages with
different character sets, and multi-media e-mail among many different
computer systems that use Internet mail standards.

If you were bored with plain text e-mail messages, thanks to MIME you
now can create and read e-mail messages containing these things:

        - character sets other than ASCII
        - enriched text
        - images
        - sounds
        - other messages (reliably encapsulated)
        - tar files
        - PostScript
        - pointers to FTPable files
        - other stuff

MIME supports not only several pre-defined types of non-textual
message contents, such as 8-bit 8000Hz-sampled mu-LAW audio, GIF image
files, and PostScript programs, but also permits you to define your
own types of message parts.

The ability to create e-mail messages with audio and other non-textual
contents has been around for a while, but almost always as part of a
vendor-specific "solution."  This means that you can't create a
message on a NeXT system containing PostScript information and "Lip
Service" (NeXT's audio e-mail tool) and easily handle the same message
on an HP 9000/710, a Sun SPARCstation IPC, and a Silicon Graphics
Iris.  That's a problem that MIME helps to solve.

One of the best things about MIME is that it's a "four-wheel drive
protocol" (to borrow a description applied originally to PhoneNet by
Einar Stefferud).  MIME was carefully designed to survive many of the
most bizarre variations of SMTP, UUCP, and Procrustean mail transport
protocols, such as BITNET and MMDF, that like to slice, dice, and
stretch the headers and bodies of e-mail messages.

Here are a few examples of how MIME is being used in the real world,
now.

1. Dr. Marshall T. Rose mails out his SNMP-related newsletter, "The
Simple Times" as multi-media e-mail messages in several forms:

        - in a PostScript form, with beautiful typesetting and a
        two-column page layout, suitable for printing on a laser
        printer;

        - in a "text/richtext" form (explained in question 3.2),
        suitable for display on a mildly intelligent ASCII terminal;
        and

        - in a plain text, ordinary message form.

(SNMP is the Simple Network Management Protocol.)

2. IETF document announcements (RFCs, Internet Drafts, etc.) are
structured as multipart MIME messages.  The first part contains the
document abstract.  The second part is itself a multipart message,
containing external references to the document itself (one via a
mail-server, one via anonymous FTP).  Thus, with a suitable UA (User
Agent, see 2.5 for glossary), you can read the abstract, and then have
the complete document retrieved for you (by the most appropriate method)
at the press of a button.

3. A "pointer" to this FAQ is posted weekly in comp.mail.mime.  The
pointer article contains MIME external contents that MIME-capable mail
user agents can use to obtain the FAQ via Internet FTP or via mail
server.

--------------------------------

2.2) MIME features that may or may not be present

Implementations of multi-media e-mail need not support the full spec;
it's possible to have a useful product that does not explore all of
the nooks and crannies of the standard.  

Furthermore, MIME permits a message to contain alternative parts for
consumption by sites that can't necessarily display or listen to all
the good stuff.
 
Here is a list of features that someone with a good, functional
mail user agent might include for MIME support.
 
 - Displays GIF, JPEG, and PBM encoded images, using e.g. 'xv' in the X
   Window System, or (name of windows program here) in Microsoft Windows.
  
 - Displays PostScript parts, using e.g. something that prints to a
   PostScript printer, or that invokes GhostScript on an X Window System
   display, or that uses Display PostScript.
  
 - Obtains external body parts via Internet FTP or via mail server.
   
 - Plays audio parts on workstations that support digital audio.

On the other hand, the minimal requirements for a MIME-conformant MUA
are almost trivial, yet still provide increased functionality.  (The
minimal requirements are mainly concerned with ensuring that users are
not shown raw data from a MIME message inappropriately.)

See also:

 - RFC 1820, the "Multimedia E-mail (MIME) User Agent Checklist",
   by Erik Huizer.

--------------------------------

2.3) Help!  I got a message in MIME format--how do I decode it?

Check out the MIME meta-FAQ, which is posted in comp.mail.mime along
with this FAQ.  The meta-FAQ offers general advice for dealing with
various MIME problems.  Of course, there are lots of options for 
decoding a MIME message, some of which are enumerated in part 2
of this FAQ.

If you receive some content type that your mail user agent can't
already handle, then you'll have to modify your global or personal
mail system configuration to deal with it--if you can.  It's not
always possible, short of spending a year of your life to write the
required programs.  But look in the MIME FAQ to see if someone already
has a tool or product that will decode the content type that you're
attempting to handle.  (Also check the MIME Meta-FAQ, go
treasure-hunting on the net, and so on.)

Here your faithful MIME FAQ maintainer feels the need to rant a bit on
the subject of poor MIME usage and concomitant MIME decoding problems.

MIME capability doesn't automatically confer interoperability with the
rest of the world.  Any random data can be mapped into MIME one way or
another, but some consideration needs to be given to the target
audiences.

Still, as Einar Stefferud likes to point out, "'Can' implies 'shall.'"
Platform or application-specific MIME data formats inevitably leak out
to the rest of the world, prompting instant FAQs: "Huh?  Now how do I
make my mail reader handle _this_?  And why was it sent to me?"

For creators of MIME messages, here are some preventive suggestions:

  - Know how your attachments are going to be sent.  Bear in mind
    that what's reasonable for another Macintosh/Windows/Envoy/Whatever
    recipient isn't necessarily reasonable for the rest of the world.
    For example, sending that Microsoft Word document as an attachment
    might not work out as well as you think it should.

  - Be somewhat conservative about content types when sending to
    mailing lists or other public forums, or consider using
    multipart/alternative.

  - Watch charset selections and content transfer encodings.
    For example, some commonly used character sets on Apple Macintosh
    computers use eight bits, not the standard seven bits, and also
    contain a few non-standard glyphs.

--------------------------------

2.4) Further information

A nice overview of the MIME specification by Mark Grand is available
from:

ftp://ftp.netcom.com/pub/md/mdg/mime.ps
ftp://ftp.netcom.com/pub/md/mdg/mime.txt

    [ Nischal Sheth <nsheth@enuxsa.eas.asu.edu> 29-May-1995 ]

    Other URLs for the PS and text versions of the document are:

    ftp://romulus.ucs.uoknor.edu/mirrors/networking/mail/mime/mime.ps
    ftp://romulus.ucs.uoknor.edu/mirrors/networking/mail/mime/mime.txt


Other information:

    [ Arjan van der Meer <arjanvdm@htsa.hva.nl> 30-Jan-1995 ]

    Mail for more info: mime-DocServer@docserver.cac.washington.edu
    It sent me a brief and clear E-mailing about how and what MIME is.

{ Any other documents that should be referenced? }

--------------------------------

2.5) MIME glossary

Every subculture needs its list of buzzwords, here's a start at a
collection for MIME.
  
body            the part of a message after the header (the "meat")
content         a portion of a MIME message
CTE             content transfer encoding (e.g. base64, quoted-printable, etc.)
ESMTP           Extended SMTP - RFC 1651
external part   a "pointer" to a part available via FTP or other means
GIF             graphical interchange format for images
header          the To, From, Subject, etc. at the start of a message
HTML            hypertext markup language; used in WWW documents
JPEG            an image compression standard for still images
mail transport  the "post office", e.g. sendmail, smail, MMDF, etc.
MIME            Multipurpose Internet Mail Extensions - RFC 1521
MPEG            an image compression standard for moving pictures
MTA             Mail Transport Agent, see "mail transport"
MUA             Mail User Agent, see "user agent"
multi-media     nebulous marketroid term meaning audio and visual stuff
part            a piece of a MIME message containing some data type
PBM             an image format
PEM             Privacy Enhanced Mail
PGP             Pretty Good Privacy
PostScript      a popular page description language
RFC             request for comments; proposed or standard Internet protocols
SMTP            Simple Mail Transfer Protocol - RFC 821
text/enriched   simple text markup language for MIME - RFC 1563
text/simplemail another (even simpler?) text markup language
URL             WWW uniform resource locator; access-method://host/path
user agent      the end user's mail program, e.g. MH, ELM, /bin/mail, etc.
WWW             the worldwide web (see section 4.4)

--------------------------------

2.6) Newsgroups and mailing lists

 - You're probably reading comp.mail.mime at the moment.  This is
   the USENET newsgroup devoted to discussions of MIME.
 
 
 - There is also a mailing list, info-mime, which is gatewayed with
   comp.mail.mime.  This is a bidirectional gateway, so every message to
   the mailing list also appears on the newsgroup, and vice versa.  If
   you are unable or unwilling to read USENET news, send subscription
   requests to:
 
         info-mime-request@cs.utk.edu
 

 - There is a UK exploder for info-mime (info-mime-uk).  Contact:
 
         info-mime-uk-request@mailbase.ac.uk
 
   The Mailbase software archives all contributions, which are then
   accessible via these URLs:
 
   ftp://mailbase.ac.uk
   gopher://mailbase.ac.uk
 
   ...and via mailserver; send a message to mailbase@mailbase.ac.uk, with
   a message body containing, e.g. "send info-mime-uk 08-1993".
 
 
 - The archive ftp://ftp.ncd.com/pub/usenet/comp.mail.mime stores
   articles in three formats: by subject, by article number, and by
   month.  See the README file for more information.
 
 
 - There is also a [comp.mail.multi-media] newsgroup, which contains
   general discussions of multi-media e-mail, not necessarily MIME.
 
 
 - There are various mailing lists specific to particular
   implementations of MIME.  If we know of such a list, it is
   mentioned in the section of this document about that
   implementation.  
--

3) Miscellaneous questions
--------------------------

3.1) What can I use to display MIME messages?
 
You need something that understands MIME-structured messages and also
understands how to display the different kinds of body parts.

Details of many freely available and commercial packages to do just
that can be found in part 2 of this FAQ.

--------------------------------

3.2) What's "text/enriched"?

The text/enriched type offers simple text markup, without making the
text unreadable to someone without the software to interpret it.
The text/enriched scheme uses markup commands enclosed in angle
brackets.  For example, here is how you would <bold>embolden</bold> a
single word.

The text/enriched type is defined in RFC 1563.  It supersedes
text/richtext, which was defined in RFC 1341.  See part 3 of this
FAQ for information about how to obtain RFCs.

A freely available implementation of a viewer for text/enriched is
part of the metamail 2.7 "richtext" program, via the undocumented
command line option "-e".  See part 2 of this FAQ for details about
metamail.

Other markup language proposals have been made.  One is simplemail,
which is more like a standardization of certain existing practices in
mail and news articles.  For example, here is how you would *emphasize* 
a single word.

Simplemail is explained in an Internet Draft by Bill Janssen and Evan
Kirshenbaum.  See part 3 of this FAQ for information about how to
obtain Internet Drafts.

--------------------------------

3.3) What about security issues?

Both users and administrators should be aware that ordinary Internet
and UUCP e-mail is not secure.  No authentication, confidentiality, or
data integrity properties are provided in SMTP, RFC 822, or MIME.
Persons desiring any or all of those security properties in their
e-mail should look into the use of Privacy-Enhanced Mail (PEM).  Other
forms of e-mail security, such as PGP (Pretty Good Privacy), are also
available.

At least one no-cost implementation of PEM is available in the US and
Canada.  There are also a number of implementations being developed in
Europe (hopefully these will not suffer the same restrictions on
export).

See also the following RFCs:
        RFC 1421 through RFC 1424 - PEM
        RFC 1847 - Security Multiparts for MIME
        RFC 1848 - MIME Object Security Services

A system providing similar functionality to PEM implementations is PGP
PGP is an implementation, not a specification, and it does not carry
the blessing of the IETF, or any other body.  It is, however,
available at no cost throughout the world (although its status with
respect to certain US patents is dubious).  Caveat emptor.

    [ "Jeffrey I. Schiller" <jis@mit.edu>  24-Jun-1994 ]

    There is now a freeware version of PGP that is not dubious from a
    patent standpoint.

Billg@yrkpa.kias.com notes the existence of the PGP FAQ from
alt.security.pgp.  In addition to enumerating various implementations,
that document indicates that information about how to obtain the
officially blessed version of PGP is available from:

    http://web.mit.edu/network/pgp-form.html

There is also an O'Reilly book out on the subject of PGP.  It
contains, among other useful information, an unflinching report
on how PGP came to be.

    [ Michael Elkins <elkins@aero.org> 18-Dec-1995 ]

    If you are interested in joining the discussion of issues on a standard
    for use of PGP to encrypt/sign Internet e-mail messages using MIME, you
    may be interested in this list.  I highly encourage everyone who is
    working on incorporating PGP into a mail client to join, even if you
    don't participate in the discussion, since it will be the best source of
    information about the developing proposed standard.
    
    To join the list, send mail to
            pgp-mime-request@lists.uchicago.edu
    with a subject of "subscribe".
    
    Submissions should be sent to
            pgp-mime@lists.uchicago.edu

{ This section needs additional information, URLs, etc. }

--------------------------------

3.4) So, does MIME introduce any new security problems?

Yes.  MIME user agents can do previously unheard of things with mail
messages, notably giving them as input to other programs.

PostScript is probably the biggest potential security hole.  One
famous example is the "melting screen" PostScript program, which
destroys screens maintained by Display PostScript implementations.  For
another example, PostScript can be used to change the password on some
PostScript printers with previously undefined passwords, which denies
the use of the printer until the printer's password can (somehow) be
changed back.  Yet other Display PostScript implementations may allow
file operations.  (NeXTstep wisely disables file operations.  With
GhostScript, they can be disabled by the "-dSAFER" command line option.
Use of this option (in mailcap, etc.) is highly recommended.)

The enumeration of these security holes is not to be interpreted as
encouragement to exploit the holes.  They are mentioned only because
they are well known.  Refer to books such as "Practical UNIX Security"
and to news groups such as comp.security.misc for general information
about system security.

--------------------------------

3.5) What about a group 3 facsimile encoding?

There is an X.400-conformant G3 facsimile type for MIME, "image/g3fax".
The specifications are in the MIME-MHS documents.

{ What current commercial and non-commercial software packages implement
  viewers or generators for the image/g3fax content type per se, as opposed
  to fax image rendering for other MIME content types?  And which of these
  interoperate with the remote printing experimental domain "TPC.INT"? }

The early MIME specification did not include a G3 facsimile type, but
there were some efforts along these lines anyway:

    [ Stuart Lynne <sl@wimsey.com> 30-Dec-1992 ]

    I have prototype scripts operating with metamail to do some of this.
    Some of it is in contrib directory.

    Currently I have 2 scripts:

        mm2fax  - convert mail and metamail messages to TIFF/F (uses various
        tools to convert different body parts to TIFF/F);

        faxmm   - send rfc822 and mime e-mail messages via facsimile (uses
        mm2fax to convert to TIFF/F).

    [ Ned Freed <ned@innosoft.com> 31-Dec-1992 ]

    PMDF-FAX is a set of channel programs for PMDF that provide
    facilities for converting text, PostScript, and various other
    formats into Group 3 FAX, as well as a set of programs that take
    these Group 3 FAX files and use them to drive a variety of FAX
    modems.  MIME is used throughout to provide type information,
    multipart facilities, and so forth. PMDF-FAX was developed with MIME
    in mind from the outset.

See also: news:comp.mail.misc - "FAQ: How can I send a fax from the Internet?"

--------------------------------

3.6) Should I always use external body parts to save space?

Not necessarily.  In many cases, for example, at the ends of UUCP
connections, your recipients may not be able to retrieve external body
parts easily.  It depends on your audience.  Making files available via
a mail server is to be encouraged.  It is always possible to provide
MIME alternative parts that first offer FTP, then mail server options.

--------------------------------

3.7) What mail servers can I reference?

There are various mail servers available.  Check news.answers for
the FAQ about mail server software.  We do not presently have a
recommendation.

--------------------------------

3.8) Can I interwork between MIME and X.400?

Conversion between RFC 822 and X.400 is defined in RFC 1327 and 
RFC 1495.

Recently, the MIME-MHS working group has published RFCs (which are on
the IAB standards track) that extend RFC 1327 to define conversions
between MIME and X.400.

Some MTAs, notably the ISODE Consortium's version of PP (see section 8)
have MIME gatewaying support.

--------------------------------

3.9) Why does MIME define base64 instead of using uuencode?

    [ Ed Greshko <egreshko@cosmo.twntpe.cdc.com> 15-Apr-1994 ]

    The *major* reason is that there is no standard for uuencode.  While
    it is popular, the many flavors of uuencode in existence make it a
    prime candidate for *non*-interoperability.

    [ John Gardiner Myers <jgm+@CMU.EDU> 1-Jun-1994 ]

    Some gateways damage messages in the more common uuencode formats.
    Gateways that convert between EBCDIC and ASCII, in particular, tend to
    damage some of the characters used in the uuencode format.  The base64
    encoding is designed to be invulnerable to all known gateways.

    [ Ned Freed <NED@innosoft.com> 26-Oct-1994 ]

    Well, once you say UUENCODE you've already bought into a whole bunch
    of different formats. There are lots of different encoders out there
    that produce completely different variants of UUENCODE. (I just ran
    into a new one I had never seen before yesterday, and it happens to be
    one I know won't work with some of the decoders I've used.)  And
    sometimes they interoperate and sometimes they don't.
    
    Because of the lack of a standard version of UUENCODE and the
    resulting interoperability problems, as well as various problems with
    the encoding character set used by some UUENCODE implementations, MIME
    elected to go with an existing encoding originally defined, if memory
    serves, in RFC989 back in 1987, as well as adding a new "lightweight"
    encoding mechanism for material that's mostly text.
    
    I should also point out that most MIME-ware supports UUENCODE as a
    format even if though it is nonstandard and causes interoperability
    problems.

    There are a bunch of other encodings in use, like base85, btoa, and
    hexadecimal.  However, you really don't see these that often in
    practice.

{ Additional information, horror stories, etc., welcome. }

--------------------------------

3.10) How can I use uuencode with MIME?

The following idea from Nathaniel may be useful.  For some examples of
this in action, see the newsgroup clari.feature.dilbert.

    [ Nathaniel Borenstein <nsb@thumper.bellcore.com> 4-Nov-93 ]

    I recently convinced myself that you can use multipart/alternative
    to get a nice effect for both MIME-smart recipients and
    uuencode-loving recipients, although it is ugly and wasteful:
    
    Content-type: multipart/alternative; boundary=foo
    
    --foo
    Content-type: application/octet-stream; name=foo.uu
    
    ...uuencoded data goes here....
    --foo
    Content-type: real-mime-type
    Content-type: base64
    
    base64-encoded data goes here
    --foo--
    
    A good MIME viewer will only use the second part, the real MIME
    data.  A uuencode-oriented system, however, should ignore everything
    EXCEPT the uuencoded data, because of the way uuencode works
    (everything before the "begin" line and after the "end" line is
    ignored).

    I certainly wouldn't want to recommend the above as standard
    practice, but I imagine that are enclaves or situations where it
    could be useful.
--

3.11) Does Microsoft Mail support MIME?

    [ Ned Freed <ned@sigurd.innosoft.com> 30-Nov-1995 ]

    Microsoft Mail doesn't provide MIME support. Microsoft Exchange may,
    although it isn't clear what form this support will take.
    
    There is a variety of solutions available from various third parties.
    I'd recommend that you peruse the MIME FAQ for this list -- it should
    suggest several starting points.
--

3.12) Can I do MIME on a (pick one) PC/Macintosh/Envoy/Whatever?

See section 2.3.

--

4) MIME information available from the Internet
-----------------------------------------------

4.1) Anonymous FTP

Information about FTPable stuff is scattered throughout this FAQ.
More specifically, look into the RFCs mentioned in part 3 of this FAQ.

Other goodies can be found in the MH and MetaMail source trees.  

Refer to part 2 of this FAQ for lots of details and URLs beginning
with "ftp:".  Refer to section 10.1 for information about how to
retrieve RFCs via FTP.

--------------------------------

4.2) Mail-based archive servers

A few Internet sites whose archives contain MIME-related information
support retrieval via e-mail servers.  One of these is ics.uci.edu.
References in URL form to ftp.ics.uci.edu may be used to formulate
retrieval requests to send to the archive-server address at
ics.uci.edu.  To find out more about how to use that mail server, send
a message whose body contains the line "help" to the address
"archive-server@ics.uci.edu".

RFCs may be requested from a mail-based archive server.  Refer to
section 10.1 for information about how to do that.

Several freely available packages, including ServiceMail and metamail,
contain mail-based archive servers.  Some commercial packages do as
well.  Refer to part 2 of this FAQ for details.  Installing a
mail-based archive server at your site makes it possible to send out
messages containing external body contents that can be used to
retrieve materials automatically from your site via e-mail.

--------------------------------

4.3) Gopher

    [ Randall Atkinson <atkinson@tengwar.itd.nrl.navy.mil> 2-Jan-1993 ]

    There is experimental work underway in the Internet Gopher community
    to include MIME as a mechanism for marking the content of files. 
    The freely distributable Gopher client for NeXTstep 3.0 includes
    MIME support.  Other gopher clients will probably add it eventually.

--------------------------------

4.4) World Wide Web

    [ Marc VanHeyningen <mvanheyn@cs.indiana.edu> 26-Jun-1993 ]

    There is more-than-experimental work underway in the Internet World
    Wide Web (WWW) community to use MIME as the mechanism for marking
    the contents of information exchanged via HyperText Transfer
    Protocol (HTTP); the specification of HTTP/1.0 dictates that both
    the request and the response are more or less MIME-compliant
    messages.  There are implementations already doing this today.

    Support is also included for format negotiation (e.g. a server
    might have both a PostScript and a plaintext version of a paper
    and decide which to send based on what the client can accept,
    presentation preferences, size, and the like.)  It's nearly as
    complicated as the "badness" mechanisms in TeX, and unrelated to
    (and, for its application, probably superior to) the
    multipart/alternative MIME type.

    There is an FAQ for WWW in comp.infosystems.www
--
    
5) Published books and articles
-------------------------------

 - Books

 The Internet Message: closing the book with electronic mail

 Marshall T. Rose
 Prentice-Hall
 ISBN 0-13-092941-7
 
 This book is a complete review of the Internet world of electronic
 mail, including recent developments.  There is considerable detail,
 and it would make the perfect companion to the mail RFCs for any
 budding implementor.
 
 On the other hand, the detail should be quite easy to skip for those
 interested in just an overview.
 
 As usual, Marshall's informed and often vigorous opinions are clearly
 marked off as "soapboxes", to be objectively skipped or delightedly
 sought out, according to preference.
 
 One chapter of the book is devoted to MIME.

 
 - Articles and Papers

    [ Daniel Glazman <Daniel.Glazman@der.edf.fr> 27-Oct-94 ]

    (In English):

        N.Borenstein, Bellcore, "Multimedia Mail From the Bottom Up or
                Teaching Dumb Mailers to Sing", ConneXions, pp. 10-16, Nov.91

        G.Vaudreuil, CNRI, "MIME: Multi-Media, Multi-Lingual Extensions for
                RFC 822 Based Electronic Mail", ConneXions, pp. 36-39, Sep.92

    (In French):

        D.Glazman, EDF/DER, "Les Extensions MIME", Tribunix No 57, Oct.94

--

6) MIME based relays for commercial mail services
-------------------------------------------------

6.1) Large national or international providers

{ There's lots missing here, and this information is aging. If anyone 
  has updated information about any of the various mail service providers
  listed here, or any others, then send 'em to the MIME FAQ Maintainer
  address <mime-faq@ics.uci.edu>. }

--------------------------------

6.1.1) ATTMAIL

    [ Steve <atthelp@attmail.com> 30-Dec-1992 ]

    We do support binary attachment but are not MIME compliant nor do
    we have an X.400 to MIME conversion header routine. This is 'in the
    works', however, and due to overwhelming interest by our users and
    other prmd's, research and development are currently engaged in
    working on the issue. I do not have any information on when this
    will be available, but will let you know when I receive word of our
    MIME status.

--------------------------------

6.1.2) CompuServe

    [ Pat Farrell <pfarrell@netcom.com> 31-Dec-1993 ]

    CompuServe's main mail service is ASCII text based, and is not MIME
    compliant. CompuServe provides robust, reliable mail transport of
    binary files. CompuServe invented and copyrighted the GIF format
    which is supported by MIME. There are commercial and freeware client
    programs for Macs and PCs that can provide "user friendly" access to
    CompuServe's text and binary mail services, display GIF files, and
    interact with CompuServe's forums. (CompuServe forums are roughly
    equivalent to USENET newsfeeds.)

--------------------------------

6.1.3) RadioMail

    [ Jerry Sweet <jsweet@irvine.com> 21-Mar-1994 ]

    RadioMail Corp. (formerly Anterior Technology) operates two types
    of e-mail services having these statuses with respect to MIME:

    1. cc:Mail/Internet gatewaying.  cc:Mail does permit binary
    attachments of various types, and these attachments are encoded by
    the gateway for transfer via SMTP, but the encoding is not presently
    MIME-compliant.  This may change.

    2. Wireless e-mail gatewaying.  Because the RadioMail gateway passes
    a limited set of headers, MIME messages per se do not traverse
    the gateway intact.  7-bit-encoded MIME messages may traverse the
    gateway if encapsulated, e.g. using RFC 934.  However, RadioMail
    does not presently supply MIME-compliant user agents for use on
    radio modem equipped MS-DOS and Macintosh computers.  This will
    change.

    [ Mark Lovell <mlovell@radiomail.net> 4-Jan-1995 ]

    The clients for both the Marco and the Envoy support a subset of MIME.
    They only support body-part types that they understand, since there is
    not a traditional OS on either unit. RadioMail has established a full
    set of MIME interface specifications, and future clients will be built
    to support them.


--------------------------------

6.2) Local and regional providers

{ Any info?  Should coordinate this with e.g. the PDIAL list. }


--
End of Part 1
*************
--
Follow-Ups: