Network Working Group
Request for Comments: 1820
Category: Informational
E. Huizer
SURFnet bv
August 1995

Multimedia E-mail (MIME) User Agent Checklist

Status of this Memo

This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. Distribution of this memo is unlimited.


This document presents a checklist to facilitate evaluation of MIME capable User Agents. Access to a MIME test-responder, that generates test-messages is described.


This document presents a checklist that facilitates evaluation of MIME capable E-mail User Agents. It is by no means a conformance or interoperability (both strictly defined and measurable quantities) checklist, but rather an interworking (practical perspective) checklist that is aimed at the users and system managers.

Usage and submission

If you use this checklist against a specific product (regardless of whether you're a vendor, implementor or user) you can submit the result to and this information will be made available (at no cost) through WWW (to be announced) for other people to browse through.

Although SURFnet will attempt to verify the correctness of each submission, all submitted, information is made available as is, with no guarantees (SURFnet does not take any responsibility for errors in the data that is made available, or for any damages resulting from usage of that data). Users who want to procure a UA are advised to use the data as an orientation, and to perform their own procurement tests (possibly using the checklist below as a guideline). Also it is noted that vendors and implementors are encouraged to use the results from the checklist to improve their products.

Getting test messages

For several tests in the checklist a test message is required. Test messages can be requested in the following way: Send mail to <mime-> with a subject field containing ONE of the following:

   X-local      <to test how your UA deals with undefined content-types>
   nested    <returns a message that contains nested multipart contents>
   iso-8859-1    <returns a message with text/plain; charset=iso-8859-1>

A message containing the requested content-type will be returned to the address contained in the from field.


The reader is encouraged to also check out the following references:

The MIME standards:

   -   Borenstein N. and N. Freed, "MIME (Multipurpose Internet
       Mail Extensions) Part One: Mechanisms for specifying and
       describing the format of Internet message bodies",  RFC 1521,
       Bellcore, Innosoft, September 1993.
   -   Moore K., "MIME (Multipurpose Internet Mail Extensions) Part
       Two: Message header extensions for non-Ascii text", RFC 1522,
       University of Tennessee, September 1993.

The registration procedure for content types:

   -   Postel J., "Media type registration procedure", RFC 1590,
       USC/Information Sciences Institute, March 1994.

Some related informational documents:

   -   Borenstein N., "The text/enriched MIME content-type",
       RFC 1563, Bellcore, October 1994.
   -   Borenstein N., "A user agent configuration mechanism for
       multimedia mail format information", RFC 1524, Bellcore,
       September 1993.
   Registered MIME content-types can be found at the following URL:
   The SUNet MIME project: This
   offers evaluation tests reports of MIME products, as well as tests
   and test-criteria for MIME implementors.
   From Stockholm University a list of user-interface requirments for a
   mail/news reader is available under: gopher://
   reports/research-reports/messaging- research

Checklist for Mime UAs

(note that for items with multiple choice options, it is possible that more than one option is applicable)

   1.  General information:
   1.1 The name and version of the product
   1.2 The name and addressing information of the manufacturer
   1.3 What are the platforms that are supported (Operating system,
       GUI and hardware requirements, if applicable: what APIs are
       supported (like MAPI etc.))?  [Note: Please use separate
       checklist forms for different platforms!!]
   1.4 What is the platform that was used for this checklist
       (Operating system, GUI and hardware)? [Note: Only one
       platform per checklist!!]
   1.5 Is the software available in source format or in binary
       format or both.
   1.6 Pricing information. Is the software available:
        - In the Public Domain, free of charge
        - As shareware (what is the price?)
        - PD for non-profit use, but not for commercial use
        - Commercially
   2.  System installation, configuration and management
   2.1 How complex/easy is installation and configuration? Are
       there any pitfalls that need attention? Can you configure
       per set of users (i.e systemwide or LAN wide default
       configuration) and/or per user?
   2.2 Are there facilities for logging and/or accounting?
   2.3 Does the UA generate correct RFC 822 headers for outgoing
       From:, (and if necessary) Sender:
   2.4 Is it possible for a non-priviledged user to change the
       "from" and/or "sender" field?
   2.5 Does the UA have any size restrictions (default or applied
       by system manager) for:
       - Message size
       - Number of messages
       - Number of folders
       - Number of messages per folder
   2.6 How secure is the users mailbox when using this UA? Can
       other non-privileged usets access the mailbox?
   2.7 What is the performance of the UA on this platform? (As this
       is difficult to measure, give your subjective impression:
       slow, reasonable or fast) E.g for:
       - Displaying a text message
       - Displaying a MIME message that contains an image
       - Complex actions like sorting etc.
   3.  General UA properties
   3.1 Does the UA have a graphical or a character based interface
       or both?
   3.2 Does the UA support native RFC 822/MIME or does it require a
   3.3 Which protocols are supported for message delivery:
        a. SMTP (MX records or static routing to Mailhost)
        b. ESMTP
        c. POP (which version)
        d. IMAP
        e. Co-location with specific MTA (which MTA)
        f. Other ...............
   3.4 Which protocols are supported for message submission:
        a. SMTP
        b. ESMTP
        c. Co-location with specific MTA (which MTA)
        d. Other ...............
   3.5 Does the UA support the following basic functionalities:
        - List messages
        - Read messages
        - Delete messages
        - Compose new messages
        - Reply to messages (Inclusion of original message-text in
          reply, reply to originator or to any or all recipients
        - Forward message
          o using MIME
          o using RFC 934 encapsulation; i.e.  message is
            encapsulated in between:
            ------- Forwarded Message  and
            ------- End of Forwarded Message
          o Other .......
        - Distribute message (the from field does not change)
   3.6 Does the UA support the following header fields and can they
       be supplied by the user:
         Generated correctly        Can be supplied by user
       - To:
       - Cc:
       - Bcc:
       - From:
       - Reply-to:
       - Subject:
       - Comments:
   3.7 Does the UA support filing mail into folders? Are there any
   3.8 Does the UA support a filtering mechanism that allows the
       user to configure automatic processing of incoming mail
       (e.g. automatic filing into specific folders)? If so, how
       simple is the configuration of these filters?
   3.9 Does the UA support a sorting mechanism that allows the user
       to sort mail on date and/or subject and/or from field etc?
       If so describe the possibilities and restrictions.
   3.10 Does the UA support address lists and/or directory services?
        - Local (local address list, local aliases, local distribution
                 lists etc.)
        - Whois++
        - Ph (to CCSO server)
        - LDAP or SOLO or other access protocols to a directory
        - Other .....
   3.11 What other non-multimedia facilities does the UA support?
   3.12 What secure mail protocols does the UA support (in-line):
       - PEM (Privacy Enhanced Mail)
       - PGP (Pretty Good Privacy)
       - Other.....
   4.  MIME support
   4.1 Does the UA support:
       - viewing a MIME content (either in-line or through launching
         an external viewer)?
       - saving a MIME content in a file?
       - saving one part of a multipart message in a file?
       - printing a MIME content?
   4.2 Does the UA support receipt of the following basic MIME
       content types? Does it display them in-line and does it
       support printing of such a content type? If an external
       viewer is needed, is a viewer pre-configured? Is the viewer
       included in the software distribution?
       In-line Printing External Preconfig Included
       - text/plain
       - text/enriched
       - image/gif
       - image/jpeg
       - audio/basic
       - video/mpeg
       - application/octet-stream
       - application/postscript
       - message/rfc822
       - message/partial
       Does the UA support ftp and/or mail access for:
       - message/external
       Describe how the UA supports the basic multipart types:
       - multipart/mixed
       - multipart/parallel
       - multipart/digest
       - multipart/alternative
       How does the UA handle:
       - X-<bilateraly defined>
       - unknown/unconfigured content-types
   4.3 Does the UA allow configuration for receipt of additional
       content-types? If so describe the configuration procedure
       and possibilities. (Is it complex/easy, give example
       configuration, can you add external viewers etc.). E.g.
       - application/wordperfect5.1
       - application/msword
   4.4 Does the UA support composition of the following basic MIME
       content types? Describe how easy/complex composition of a
       message with a MIME content-type is.
       - text/plain
       - text/enriched
       - image/gif
       - image/jpeg
       - audio/basic
       - video/mpeg
       - application/octet-stream
       - application/postscript
       - message/rfc822
       - message/partial
       - message/external
       - multipart/mixed
       - multipart/parallel
       - multipart/digest
       - multipart/alternative
       Does the UA generate X-<bilaterally defined> content-types
       (when and why)
   4.5 Does the UA support compostion of additional content-types?
       If so describe how to do this (configuration and/or
       compostion), e.g.:
       - application/wordperfect5.1
       - application/msword
   4.6 What content-encodings does the UA support:
       - 7bit
       - quoted printable
       - base64
       - binary
       - 8bit
       - X-<bilateraly defined> (when and why)
   4.7 What encoding is used for the following content-types:
         7bit QP   B64   Binary 8-bit Other
       - text/plain
       - text/enriched
       - image/gif
       - image/jpeg
       - audio/basic
       - video/mpeg
       - application/octet-stream
       - application/postscript
       - message/rfc822
       - message/partial
       - message/external
       - multipart/mixed
       - multipart/parallel
       - multipart/digest
       - multipart/alternative
   4.8 Does the UA generate the correct Mime version header:
       Mime-Version: 1.0
   4.9 In multipart messages, give an example of the sort of
       boundary string generated.
   4.10 Does the UA support the use of non-ascii characters in the
        headers (in subject, free form part of address etc.)?
   4.11 With the content type text/plain it is possible to have a charset
        parameter, indicating that a specific character set is used in

the content type text plain. What character sets (like

iso-8859-1) does the UA support (standard or configurable)?

Security Considerations

Testing a MIME UA against this checklist involves the security risks that are described in the MIME specification (RFC 1521). Most notably the automatic execution of general-purpose PostScript interpreters entails serious security risks. The reader is encouraged to read RFC 1521 for more detail on these security risks.

Author's Address

   Erik Huizer
   SURFnet bv
   P.O. Box 19035
   3501 DA  Utrecht
   The Netherlands
   Phone: +31 30 305305
   Fax: +31 30 305329