mh-mail(4)mh-mail(4)NAMEmh-mail - Message format for the MH message system
MH processes messages in a particular format. Although neither Bell
nor Berkeley mailers produce message files in the format that MH
prefers, MH can read message files in that format.
Each user has a maildrop that initially receives all messages processed
by the post command (see post(8)).
The inc command reads from the maildrop and incorporates the new mes‐
sages found there into the user's own +inbox folder. The maildrop con‐
sists of one or more messages.
Messages are expected to consist of lines of text. Graphics and binary
data are not handled. No data compression is accepted. All text is in
ASCII 7-bit data.
The general memo framework of RFC 822 is used. A message consists of a
block of information in a rigid format, followed by general text with
no specified format. The rigidly-formatted first part of a message is
called the message header; the free-format portion is called the body.
The header must always exist, but the body is optional. These parts
are separated by a blank line or by a line of dashes. The following
example shows the standard default MH mail header:
To: cc: Subject: --------
The header is composed of one or more header items. Each header item
can be viewed as a single logical line of ASCII characters. If the
text of a header item extends across several real lines, the continua‐
tion lines are indicated by leading spaces or tabs.
Each header item is called a component and is composed of a keyword or
name, along with associated text. The keyword begins at the left mar‐
gin, and is terminated by a colon (:). It cannot contain spaces or
tabs, and cannot exceed 63 characters, as specified by RFC 822.
The text for most formatted components, such as Date: and Message-Id:,
is produced automatically. The user enters address fields such as To:
and cc:, and the Subject: field. Internet addresses are assigned mail‐
box names and host computer specifications. The general format is
local@domain, for example, MH@UCI or MH@UCI-ICSA.ARPA. A comma (,)
separates multiple addresses. A missing host/domain is assumed to be
the local host/domain.
A blank line (or a line of dashes) signals that all following text up
to the end of the file is the body of the message. No formatting is
expected or enforced within the body.
The following is a list of header components that are considered mean‐
ingful to MH programs: Added by post, contains the date and time of the
message's entry into the transport system. Added by post, contains the
address of the author or authors (there may be more than one if a
Sender: field is present). Replies are typically directed to addresses
in the Reply-To: or From: field. The former has precedence, if present.
Added by post in the event that the message already has a From: line.
This line contains the address of the actual sender. Replies are never
sent to addresses in the Sender: field. Contains addresses of primary
recipients. Contains addresses of secondary recipients. Contains the
addresses of recipients who receive blind carbon copies of the message.
The Bcc: line does not appear on the message as sent, so these recipi‐
ents are not listed. Recipients in the Bcc: field receive a copy of
the message with a minimal header. MH uses an encapsulation method for
blind copies; see send(1). Causes post to copy the message into the
specified folder for the sender, if the message was successfully given
to the transport system. A unique message identifier added by post, if
the -msgid flag is set. Sender's commentary. It is displayed by scan.
A commentary line added by repl when replying to a message. Added by
post when a message is redistributed. Added by post when a message is
redistributed. New recipients for a message resent by dist. New sec‐
ondary recipients for a message resent by dist. New blind carbon copy
recipients for a message resent by dist. Places a copy of a message
resent by dist into the sender's folder. A unique identifier of a mes‐
sage resent by dist. This is appended by post if the -msgid flag is
set. Annotation added by dist when the -annotate flag is specified.
Annotation added by forw when the -annotate flag is specified. Annota‐
tion added by repl when the -annotate flag is specified. Specifies the
MIME version number. This header entry is used or added by MH software
only when codeset conversion of mail messages is enabled and requested.
For more information on codeset conversion, see the section on interna‐
tionalization features in mh(1). Specifies the content type, which is
always TEXT/PLAIN, plus a charset value that names a coded character
set (codeset). This header entry is used or added by MH software only
when codeset conversion of mail messages is enabled and requested. For
more information on codeset conversion, see the section on internation‐
alization features in mh(1).
Standard location of mail drop
Standard for the Format of ARPA Internet Text Messages (RFC 822) delim