The ContentType property returns the MIME type for the
currently selected message part. The type string consists of a
primary type and secondary sub-type separated by a slash, followed
by one or more optional parameters delimited by semi-colons. For
example, the most common content type for text messages is
indicated as:
text/plain;
charset=us-ascii
The text designation indicates that this message part
contains readable text, and the plain sub-type indicates
that the text does not contain any special encoding. The optional
parameter which follows the content type provides additional
information about the content. In this example, it specifies which
character set should be used to display the text. The two common
character sets used are ISO-8859 and US-ASCII (which is the default
character set that is used if none is specified).
There are seven predefined, standard content types, each with
their own sub-types. The following table lists these types, along
with some common sub-types that are found in messages:
| Type |
Sub-Types |
Description |
| text |
plain, richtext, html |
Indicates that the message part contains text.
This is the most common type found in mail messages; if no content
type is explicitly defined, then it is assumed to be plain
text |
| image |
gif, jpeg |
Indicates that the message part contains a
graphics image |
| audio |
basic, aiff, wav |
Indicates that the message part contains audio
data; the basic sub-type is 8-bit PCM encoded audio (commonly found
with the .au filename extension) |
| video |
mpeg, avi |
Indicates that the message part contains a
video clip in the specified format |
| application |
octet-stream, postscript |
Indicates that the message part contains
application specific data, typically used with the octet-stream
sub-type to indicate binary file attachments for executable
programs, compressed file archives, etc. |
| message |
rfc822 |
Indicates that the message part contains a
complete RFC 822 compliant message, complete with headers |
| multipart |
mixed, alternative |
Indicates that this is part of a mixed message
(a message that contains multiple parts of different content
types) |
The three most common content types that are used in applications
are text/plain for the mail message body, application/octet-stream
for binary file attachments and multipart/mixed for messages that
contain both text and attached files. For more information about
the different content types, refer to the Multipurpose Internet
Mail Extensions (MIME) standards document RFC 1521.