Provided by: nmh_1.7.1-12_amd64 bug


       mh-mail - message format for nmh message system


       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 <>
            Fcc: +outbox

       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

       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

       Following is a list of header components that are considered  meaningful  to  various  nmh

            Added  by post, contains date and time of the message's entry into the mail transport

            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.

            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.

            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:”.

            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.

            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:”.

            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

            Contains addresses of primary recipients.

            Contains addresses of secondary recipients.

            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).

            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.

            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 when redistributing a message by post.

            Used instead of the “From:” header when post redistributes a message.  See “From:”.

            New recipients for a message resent by dist.

            Still more recipients.  See “cc:” and “Resent-To:”.

            Even more recipients.  See “Bcc:” and “Resent-To:”.

            Copy resent message into a folder.  See “Fcc:” and “Resent-To:”.

            A unique identifier glued on by post if the -msgid flag is  set.   See  “Message-Id:”
            and “Resent-To:”.

            Annotation for dist under the -annotate option.

            Annotation for forw under the -annotate option.

            Annotation for repl under the -annotate option.

            Used  by mhbuild to specify a filename to attach to this message.  See mhbuild(1) for
            more information.


       /var/mail/$USER     Location of mail drop.


       Standard for the Format of ARPA Internet Text Messages (RFC 822)