MH-MAIL(5)MH-MAIL(5)NAMEmh-mail - message format for nmh message system
DESCRIPTION
nmh processes messages in a particular format. It should be noted that
although neither Bell nor Berkeley mailers produce message files in the
format that nmh prefers, nmh can read message files in that antiquated
format.
Each user possesses a mail drop box which initially receives all mes‐
sages processed by post. Inc will read from that drop box and incorpo‐
rate the new messages found there into the user's own mail folders
(typically “+inbox”). The mail drop box consists of one or more mes‐
sages.
Messages are expected to consist of lines of text. Graphics and binary
data are not handled. No data compression is accepted. All text is
clear 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 header, and the free-format portion is called the body. The
header must always exist, but the body is optional. These parts are
separated by an empty line, i.e., two consecutive newline characters.
Within nmh, the header and body may be separated by a line consisting
of dashes:
From: Local Mailbox <user@example.com>
To:
cc:
Fcc: +outbox
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, may NOT contain spaces or tabs, may not exceed 63 characters (as
specified by RFC 822), and is terminated by a colon (`:'). Certain
components (as identified by their keywords) must follow rigidly
defined formats in their text portions.
The text for most formatted components (e.g., “Date:” and “Mes‐
sage-Id:”) is produced automatically. The only ones entered by the
user are address fields such as “To:”, “cc:”, etc. Internet addresses
are assigned mailbox names and host computer specifications. The rough
format is “local@domain”, such as “MH@UCI”, or “MH@UCI-ICSA.ARPA”.
Multiple addresses are separated by commas. A missing host/domain is
assumed to be the local host/domain.
As mentioned above, a blank line (or a line of dashes) signals that all
following text up to the end of the file is the body. No formatting is
expected or enforced within the body.
Following is a list of header components that are considered meaningful
to various nmh programs.
Date:
Added by post, contains date and time of the message's entry into
the mail transport system.
From:
This header is filled in by default with the system's idea of the
user's local mailbox. This can be changed with the Local-Mailbox
profile entry. It contains the address of the author or authors
(may be more than one if a “Sender:” field is present). For a
standard reply (using repl), the reply address is constructed by
checking the following headers (in this order): “Mail-Reply-To:”,
“Reply-To:”, “From:”, “Sender:”. A “From:” header MUST exist when
the message is sent to post, otherwise the message will be
rejected.
Envelope-From:
Used by post to specify a value for the sender's envelope address
to the mail transport system. If omitted, post will use the value
of the “Sender:” or the “From:” header. See send(1) for more
details.
Mail-Reply-To:
For a standard reply (using repl), the reply address is con‐
structed by checking the following headers (in this order): “Mail-
Reply-To:”, “Reply-To:”, “From:”, “Sender:”.
Mail-Followup-To:
When making a “group” reply (using repl -group), any addresses in
this field will take precedence, and no other reply address will
be added to the draft. If this header is not available, then the
return addresses will be constructed from the “Mail-Reply-To:”, or
“Reply-To:”, or “From:”, along with adding the addresses from the
headers “To:”, “cc:”, as well as adding your personal address.
Reply-To:
For a standard reply (using repl), the reply address is con‐
structed by checking the following headers (in this order): “Mail-
Reply-To:”, “Reply-To:”, “From:”, “Sender:”.
Sender:
Required by post in the event that the message has multiple
addresses on the “From:” line. It is otherwise optional. This
line should contain the address of the actual sender.
To:
Contains addresses of primary recipients.
cc:
Contains addresses of secondary recipients.
Bcc:
Still more recipients. However, the “Bcc:” line is not copied
onto the message as delivered, so these recipients are not listed.
nmh uses an encapsulation method for blind copies, see send(1).
Dcc:
Still more recipients. However, the “Dcc:” line is not copied
onto the messages as delivered. Recipients on the “Dcc:” line
receive the same messsage as recipients on the “To:” and “cc:”
lines. See send(1) for more details. Dcc is not supported with
the sendmail/pipe mail transport method.
Fcc:
Causes post to copy the message into the specified folder for the
sender, if the message was successfully given to the transport
system.
Message-ID:
A unique message identifier added by post if the -msgid flag is
set.
Subject:
Sender's commentary. It is displayed by scan.
In-Reply-To:
A commentary line added by repl when replying to a message.
Resent-Date:
Added when redistributing a message by post.
Resent-From:
Used instead of the “From:” header when post redistributes a mes‐
sage. See “From:” for more information about this header is used.
Resent-To:
New recipients for a message resent by dist.
Resent-cc:
Still more recipients. See “cc:” and “Resent-To:”.
Resent-Bcc:
Even more recipients. See “Bcc:” and “Resent-To:”.
Resent-Fcc:
Copy resent message into a folder. See “Fcc:” and “Resent-To:”.
Resent-Message-Id:
A unique identifier glued on by post if the -msgid flag is set.
See “Message-Id:” and “Resent-To:”.
Resent:
Annotation for dist under the -annotate option.
Forwarded:
Annotation for forw under the -annotate option.
Replied:
Annotation for repl under the -annotate option.
Attach:
Used by mhbuild to specify a filename to attach to this message.
See mhbuild(1) for more information.
FILES
/var/mail/$USER Location of mail drop
SEE ALSO
Standard for the Format of ARPA Internet Text Messages (RFC 822)
CONTEXT
None
nmh-1.6 January 8, 2014 MH-MAIL(5)
