Document: FSC-0056+ Version: 001 Date: 29-Apr-2021

                     EMSI/IEMSI Protocol Extension
                       George E. "Ozz" Nixon Jr.
                            April 29, 2021

  Status of this document:

   This FSC suggests an extension to the existing EMSI protocol for the
   FidoNet(r) community, and requests discussion and suggestions for
   improvements. Distribution of this document is subject to the
   restrictions specified on the next page.

   Fido and FidoNet are registered marks of Tom Jennings and Fido
   Software.

    (Also known as EMSC-001; Electronic Mail Standards Document #001)
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      Copyright 2021 George E. "Ozz" Nixon Jr. All rights reserved.
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  Preface
  =====================================================================
  While developing Rhenium F8 mailer, it became apparent that unless it
  was being tested against an existing EMSI mailer nearby, it was next
  to impossible to know on the caller side why a session would stall in
  what appears to be a successful exchange of the EMSI_DAT packet. When
  having a machine nearby to test, it always appears to be a password
  related issue. Thus, I am proposing an extension to the protocol that
  will inform the caller system what is wrong with the session password
  exchange.

  =====================================================================
  EMSI Error Expected Password                    **EMSI_EEP<crc16><CR>
  ---------------------------------------------------------------------
  The answering machine has a session password for either the callers
  main address or one or more AKAs. The caller side did not present a
  password in the EMSI_DAT. EMSI_EPP reports to the caller why there
  was an error and the session terminated.

  =====================================================================
  EMSI Unexpected Password Continue               **EMSI_UPC<crc16><CR>
  ---------------------------------------------------------------------
  The answering machine does not have a session password for either the
  callers main address or one or more AKAs. The caller side presented a
  password in the EMSI_DAT. EMSI_UPC reports to the caller there is an
  inconsistency, however, the session may continue until a password is
  required. This is for the case of a new system polling or doing FREQ
  for a nodelist for example.

  =====================================================================
  EMSI Error Unexpected Password                  **EMSI_EUP<crc16><CR>
  ---------------------------------------------------------------------
  The answering machine does not have a session password for either the
  callers main address or one or more AKAs. The caller side presented a
  password in the EMSI_DAT. EMSI_EUP reports to the caller there is an
  inconsistency, and the session terminated.

  =====================================================================
  EMSI Invalid Session Password                   **EMSI_ISP<crc16><CR>
  ---------------------------------------------------------------------
  The answering machine does not have a matching session password for
  either the callers main address or one or more AKAs. The caller side
  presented an incorrect password in the EMSI_DAT. EMSI_ISP reports to
  the caller there is an inconsistency, and the session terminated.

– end of “emsi+.txt” –