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 antiquated format.

       Each  user  possesses  a  mail drop box which initially receives all messages processed by
       post.  Inc will read from that drop box and incorporate the new messages found there  into
       the  user's  own  mail folders (typically “+inbox”).  The mail drop box 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 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 message.  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