HP 3000 Manuals

Installing and Configuring HP X.400 Administrator's Guide

X.400 Message 

The CCITT X.400 standard specifies the two basic components of an X.400
message as:

   *   Envelope, which contains the information required to deliver a
       message.

   *   Content, which contains the information to be delivered.

Figure 2-6 shows the components that make up the X.400 message.  It also
compares the content layout for a typical memo and the content format
called InterPersonal Message (IPM), which is used for electronic mail
applications.


          Figure 2-6.  X.400 Message Components and IPM Content 

Envelope 

The envelope contains the information required to deliver the message.
The primary information is the address information of the originator and
recipients.  The envelope also contains other information, such as
Priority, which an MTA uses to determine HOW a message should be
delivered, or Submission Time, which indicates WHEN a message was
originally submitted to an MTA. This is analogous to a normal U.S. postal
envelope, which contains destination and return address, a postmark, and
an indication of the class of delivery (First Class, etc.).

Envelope information which provides Message Transfer Service Elements is
used primarily by the MTA. Arrival Time and Priority provide the
Submission time stampand Grade of delivery Message Transfer Service
elements.

Contents 

The contents of an X.400 message contain the actual information to be
delivered and may have any format.  The 1984 X.400 recommendations
specify one content format called IPM which is useful for electronic
mail.  Eventually there may be other contents specified, such as
Electronic Document Interchange (EDI), which may be useful for common
types of business forms.  Currently, any content other than IPM is
treated as undefined.

The contents of a message are off-limitsto the MTA and used only by the
UA. All the information in the contents is used to provide IPM Service
Elements.  An indicator of the type of contents contained in a message
appears in the envelope for the use of the MTA. Each UA registers the
content typesthat it supports, and the MTA compares this registration to
the content indicatorto determine if the message can be delivered to the
UA. IPM contents are defined in terms of a heading and a body.

IPM Heading.     

The heading of an IPM message contains information like that contained in
a letterhead, or the top part of an interoffice memo.  The primary pieces
of information are the name and addresses of the message originator and
all the recipients.  This address information contained in the heading is
not used by the MHS in the delivery of the message.  It is just for
informational use by the UA.

Other heading information includes Sensitivity, which tells the UA
whether the message is private, and Reply Request, which indicates that a
reply to this message was requested by the originator.

IPM Body.     

The actual IPM message body consists of an indicator of the body's data
type and the data itself.  Some message bodies consist of simple 7-bit
ASCII types and extended 8-bit ASCII types, which support many European
languages and application-private body types.  An IPM message may have an
unlimited number of bodies, which may be of different types.

See the "Available X.400 Features on Mailx or Elm" section in Appendix F
of this manual for the message bodies (body parts) available on HP's
X.400/9000 for sending, receiving, and routing using mailx or elm.

MPE/iX 5.0 Documentation