August 13, 1982              - 16 -                      RFC #822
 

 
     Standard for ARPA Internet Text Messages


     4.  MESSAGE SPECIFICATION

     4.1.  SYNTAX

     Note:  Due to an artifact of the notational conventions, the syn-
            tax  indicates that, when present, some fields, must be in
            a particular order.  Header fields  are  NOT  required  to
            occur  in  any  particular  order, except that the message
            body must occur AFTER  the  headers.   It  is  recommended
            that,  if  present,  headers be sent in the order "Return-
            Path", "Received", "Date",  "From",  "Subject",  "Sender",
            "To", "cc", etc.

            This specification permits multiple  occurrences  of  most
            fields.   Except  as  noted,  their  interpretation is not
            specified here, and their use is discouraged.

          The following syntax for the bodies of various fields should
     be  thought  of  as  describing  each field body as a single long
     string (or line).  The "Lexical Analysis of Message"  section  on
     "Long  Header Fields", above, indicates how such long strings can
     be represented on more than one line in  the  actual  transmitted
     message.

     message     =  fields *( CRLF *text )       ; Everything after
                                                 ;  first null line
                                                 ;  is message body

     fields      =    dates                      ; Creation time,
                      source                     ;  author id & one
                    1*destination                ;  address required
                     *optional-field             ;  others optional

     source      = [  trace ]                    ; net traversals
                      originator                 ; original mail
                   [  resent ]                   ; forwarded

     trace       =    return                     ; path to sender
                    1*received                   ; receipt tags

     return      =  "Return-path" ":" route-addr ; return address

     received    =  "Received"    ":"            ; one per relay
                       ["from" domain]           ; sending host
                       ["by"   domain]           ; receiving host
                       ["via"  atom]             ; physical path
                      *("with" atom)             ; link/mail protocol
                       ["id"   msg-id]           ; receiver msg id
                       ["for"  addr-spec]        ; initial form


     August 13, 1982              - 17 -                      RFC #822
 

 
     Standard for ARPA Internet Text Messages


                        ";"    date-time         ; time received

     originator  =   authentic                   ; authenticated addr
                   [ "Reply-To"   ":" 1#address] )

     authentic   =   "From"       ":"   mailbox  ; Single author
                 / ( "Sender"     ":"   mailbox  ; Actual submittor
                     "From"       ":" 1#mailbox) ; Multiple authors
                                                 ;  or not sender

     resent      =   resent-authentic
                   [ "Resent-Reply-To"  ":" 1#address] )

     resent-authentic =
                 =   "Resent-From"      ":"   mailbox
                 / ( "Resent-Sender"    ":"   mailbox
                     "Resent-From"      ":" 1#mailbox  )

     dates       =   orig-date                   ; Original
                   [ resent-date ]               ; Forwarded

     orig-date   =  "Date"        ":"   date-time

     resent-date =  "Resent-Date" ":"   date-time

     destination =  "To"          ":" 1#address  ; Primary
                 /  "Resent-To"   ":" 1#address
                 /  "cc"          ":" 1#address  ; Secondary
                 /  "Resent-cc"   ":" 1#address
                 /  "bcc"         ":"  #address  ; Blind carbon
                 /  "Resent-bcc"  ":"  #address

     optional-field =
                 /  "Message-ID"        ":"   msg-id