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Sendmail, 3rd Edition by Bryan Costales

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The V Configuration Command

The V configuration command was added to V8 sendmail to prevent old versions of configuration files from breaking when used with V8 sendmail. The syntax for the V configuration command looks like this:

Vlevel               V8.1 through V8.5
Vlevel/vendor        V8.6 and above

We describe the level and vendor parts in the next two sections.

The V Configuration Command’s Level Part

The level is a positive integer. If level is higher than the maximum allowed for the current version, sendmail prints the following warning and accepts the value:

Warning: .cf version level (lev) exceeds program functionality (max)

If level is less than 0 or if the V configuration command is omitted, the default level is 0.

The effects of the various version levels are relatively minor. As sendmail continues to develop, they might become more pronounced. Currently, the version levels are as follows:

0

The check for a valid shell in /etc/shells is ignored (Section 10.8.3).

0 through 1

MX records are looked up with the RES_DEFNAMES and RES_DNSRCH cleared. The high bit is always stripped from the body of every mail message.

2 and above

The sendmail program automatically adds a -a. to the "host host" database map (Section 23.4.3) declaration, if that database map isn’t declared in the configuration file. RES_DEFNAMES and RES_DNSRCH are not turned off as they were for older versions. Rule set 5 (Section 19.6) behavior is enabled.

0 through 2

Sets the UseErrorsTo option (UseErrorsTo) to true automatically. ...

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