PC Ext: Purpose and Function of -V20 Switch

• Microsoft Mail for PC Networks, versions 2.1, 3.0, and 3.2

SUMMARY

This article describes the purpose and function of the -V20 or CompatV20 switch used with the EXTERNAL.EXE program for versions 2.1, 3.0, and 3.2 of Microsoft Mail for PC Networks.

MORE INFORMATION

To remain compatible with Microsoft Mail version 2.0 and related gateway programs, Microsoft Mail for PC Networks, versions 2.1 and later requires the use of the -V20 (CompatV20 in EXTERNAL.INI file) command-line option. Current versions of Microsoft Mail for PC Networks (versions 2.1 and later) are still compatible with the previous Microsoft product (version 2.0). This compatibility means that version 2.0 of Microsoft Mail should be able to transfer mail to a later version of Microsoft Mail using the latest version of the Microsoft Mail Message Transfer Agent (MTA), EXTERNAL.EXE.

To remain compatible with version 2.0 Mail and related gateway programs, Microsoft Mail for PC Networks versions 2.1 and later allow the use of the -V20 command line option (or CompatV20 in the EXTERNAL.INI file). This option allows the later versions of the External program to use the same type of file creation, detection, and deletion algorithms that the version 2.0 used.

One function of External is to deliver mail to individual mailbags on a given mail server. In order to do this, there has to be some mechanism by which External keeps a mailbag open to put data into it. The MTAs that shipped with version 2.0 of Microsoft Mail used a different mechanism to "lock" mailbags than later versions use. This mechanism relied on file creation, detection, and deletion to prevent "mailbag contention" (more than one process trying to access the same mailbag at a time). Microsoft Mail for PC Networks versions 2.1 and later rely on the file locking capabilities provided by the specific network operating system to accomplish this task.

Therefore, because of the way in which the version 2.0 EXTERNAL.EXE locked files, using the -V20 switch generally means that EXTERNAL.EXE will exhibit performance degradation and be more input/output intensive. Because of this, Microsoft discourages the use of the -V20 switch unless a version 2.0 postoffice or gateway is involved.

If the -V20 switch is used for compatibility with version 2.0 postoffices or gateways, it MUST also be used on all other MTA processes that interact with them. For example, if the -V20 switch is used in a local area network, it will probably be needed on all the EXTERNAL.EXE processes.

Notes:

• Whenever possible, run the latest release of EXTERNAL.EXE or any gateway software for Microsoft Mail for PC Networks.
• Version 2.0 of the Microsoft Mail for PC Networks products require the -V20 switch, versions 2.1 and later do not require it.
• For FFAPI-based gateways, check the version of the FFAPI component by typing the following command:

        FFAPI_program -ver
  

  For example,

        P:\MAILEXE\GTWGET -VER