Network Working Group N. Borenstein, Bellcore
Request for Comments: 1344 June 1992
Implications of MIME for Internet Mail Gateways
Status of This Memo
This is an informational memo for the Internet community,
and requests discussion and suggestions for improvements.
This memo does not specify an Internet standard.
Distribution of this memo is unlimited.
Abstract
The recent development of MIME (Multipurpose Internet Mail
Extensions) offers a wide range of new opportunities for
electronic mail system systems. Most of these opportunites
are relevant only to user agents, the programs that interact
with human users when they send and receive mail. However,
some opportunities are also opened up for mail transport
systems. While MIME was carefully designed so that it does
not require any changes to Internet electronic message
transport facilities, there are several ways in which
message transport systems may want to take advantage of
MIME. These opportunities are the subject of this memo.
Background -- The MIME Format
Recently, a new standardized format has been defined for
enhanced electronic mail messages on the Internet. This
format, known as MIME, permits messages to include, in a
standardized manner, non-ASCII text, images, audio, and a
variety of other kinds of interesting data.
The MIME effort was explicitly focused on requiring
absolutely no changes at the message transport level.
Because of this fact, MIME-format mail runs transparently on
all known Internet or Internet-style mail systems. This
means that those concerned solely with the maintenance and
development of message transport services can safely ignore
MIME completely, if they so choose.
However, the fact that MIME can be ignored, for the purpose
of message transport, does not necessarily mean that it
should be ignored. In particular, MIME offers several
features that should be of interest to those responsible for
message transport services. By exploiting these features,
transport systems can provide certain additional kinds of
service that are currently unavailable, and can alleviate a
few existing problems.
The remainder of this document is an attempt to briefly
point out and summarize some important ways in which MIME
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