RFC-822
Standard for Internet Text Messages
Contents
Introduction
The RFC-822
document sets out the standard format for textual
Internet email messages.
In this environment a mail message is viewed as having an envelope and
contents. The envelope contains the information necessary in order to
send the message to the intended recipient, whilst the contents make up
the message to be sent.
The message is separated from its message header by a null line. That is
a line with nothing precedeing the CRLF (Carrige-Return Line-Feed).
Header Fields
Each header field in a mail message is a single line of ASCII
characters, composed of a field name and a field body.
The following fields are those most commonly included in a mail message.
They are divided into two sections :
This list of fields is not exhaustive. For a fuller description see the
RFC-822 document.
System Fields
These fields are generally added by the system
- Return-Path : This is added by the final transport system
that delives the message to its intended recipient. It contains
definitive information about the address and route back to the
originator of the message.
- Received : This field is added by each transport service that
the message passes through. It is most useful in tracing the path of a
message and consequently tracing transport problems.
- Date : This field simply indicates the date and time at which
the message was originally sent.
- Message-Id : Message-Id contains a unique identifier which
refers to this version of this message. The message-id is guaranteed to
be unique by the host which reads it.
- Reply-To : This field indicates any mailbox(es) to which
replys are to be sent.
- From : This field contains the identity of the person who
originally sent the message. If this field is not present, then the
Sender field must be included.
- Sender : This field contains the identity of the agent
(i.e. person, system or process) which sends the message. It is
generally used when the sender of a message is not the author of a
message. If the contents of the From field would make this field
redundant, then the Sender field can be ommitted.
User Fields
These following fields are those that are generally manipulated by the
person who sends a message.
- To : This field contains the name of the intended recipient of
the message.
- CC : This field indicates the name(s) of secondary recipients
of the message if any. (CC - Carbon Copy)
- Subject : The Subject field is intended to provide a summary
or an indication of the content of a message.
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