NAME

       mh-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
       format.

       Each user possesses a mail drop which initially receives all messages processed by post.  inc  will  read
       from  that mail drop and incorporate new messages found there into the user's own mail folders (typically
       “+inbox”).  The mail drop consists 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 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
       continuation 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 margin, 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 “Message-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  constructed  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  constructed  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 message 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 message.  See “From:”.

       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-1.8                                            2014-01-08                                       MH-MAIL(5mh)