Qualcomm 4.3 user manual Mime Labeling, Practical Issues

Eudora User Manual MIME Labeling

This corruption happens because SMTP cannot handle the special characters. However, if you and your recipient both have MIME, quoted-printable encoding would be used, and your text would show up properly:

«Il est démontré, disait-il, que les choses ne peuvent être autrement; car tout étant fait pour une fin, tout est nécessairement pour la meilleure fin.»

While your mail was actually in transit, however, it would have looked like:

=ABIl est d=E9montr=E9, disait-il, que les choses ne

peuvent =EAtre =autrement; car tout =E9tant fait pour une fin, tout est n=E9cessairement =

pour la meilleure fin.=BB

Base64 encoding is another way to protect binary data from the SMTP mail system. However, Base64 makes no attempt to be legible, and is most appropriate for non-text data.

MIME Labeling

The other important part of MIME is that it lets mailers communicate what kind of data is in a message (or part of a message). The primary mechanism used for this is the Content-Type header:

Content-Type: text/plain; charset=iso-8859-1

A content-type header is divided into three parts; the content type, the content subtype, and the parameters. In this case, the content type is “text,” meaning the message contains mostly legible text. The content subtype is “plain,” which means there aren’t any formatting commands or anything like that embedded in the text. Finally, “charset=iso-8859-1” is a parameter; in this case, it identifies the character set the message uses.

The major content types are:

text, legible text

image pictures and graphics

audiosound

video moving pictures

message, messages, or pieces of messages

multipart,several different kinds of data in a single message

Practical Issues

There are really only two things you sometimes need to do with Eudora and MIME. One is that it may occasionally be necessary to turn off quoted-printable encoding. Another is that you may want to know how to define mappings between computer file extensions, MIME types, and Macintosh types.

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