To provide compatibility with old configuration files, the V line has been added to define some very basic semantics of the configuration file. These are not intended to be long term supports; rather, they describe compatibility features which will probably be removed in future releases.
Old configuration files are defined as version level one. Version level two files make the following changes:
Version level four configurations are completely equivalent to level three for historical reasons.
Version level five configuration files change the default definition of $w to be just the first component of the hostname.
Version level six configuration files change many of the local processing options (such as aliasing and matching the beginning of the address for vertical bar/pipe (|) characters) to be mailer flags; this allows fine-grained control over the special local processing. Level six configuration files may also use long option names. The ColonOkInAddr option (to allow colons in the local-part of addresses) defaults on for lower numbered configuration files; the configuration file requires some additional intelligence to properly handle the RFC822 group construct.
Version level seven configuration files used new option names to replace old macros $e became SmtpGreetingMessage, $l became UnixFromLine and $o became OperatorChars. Also, prior to version seven, the F=q flag (use 250 instead of 252 return value for SMTP VRFY commands) was assumed.
Version level eight configuration files allow $# on the left hand side of ruleset lines.
Version level nine configuration files allow parentheses in rulesets (that is, they are not treated as comments and hence removed).
The V line may have an optional /vendor to indicate that this configuration file uses modifications specific to a particular vendor.
Vendors are encouraged to add themselves to the list of recognized vendors by editing the routine setvendor in conf.c. Please send email to sendmail@Sendmail.ORG to register your vendor dialect.
You may use /Berkeley to emphasize that this configuration file uses the Berkeley dialect of sendmail(1M).