[Appendix D] D.2 Backward Compatibility
Author: Bryan Costales & Eric Allman
Date: 1999-01-06T22:50:17Z

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| Appendix D Sun Enhancements |

## D.2 Backward Compatibility

Pre-V8 versions of sendmail possessed many assumptions and restrictions that modern versions have fixed, added, or eliminated. Prior to Solaris 2.5, Sun used a sendmail that was based on V5 sendmail and highly modified to satisfy Sun's other enhancements to UNIX.

To support old configuration files that were based on that old version of sendmail, Sun offers the V1/Sun version configuration command. The backward compatibility that V1/Sun mode supplies is shown in Table 38.5.

Table D.2: V1/Sun Backward Compatibility
What | Description
--- | ---
`$k` | The `$k` macro contains the value of the mail hub machine (see Section 38.18, "The > Option").
`$m` | The `$m` macro contains the same value as `${pd}` described above.
`$%` | The `$%` prefix can be used in the LHS to evaluate the `$%l`, `$%y`, and `$%z` macros.
`${` | `${` and `$}` are a synonym for `$(` and `$)` (see Section 33.4, "Use Maps with $( and $) in Rules").
`$j` | The `$j` macro (see Section 31.10.20, $j) is not automatically included in `$=w` (see Section 32.5.8, $=w), nor is it required to contain a dot.
`owner-` | The `owner-` (see Section 25.3, "Defining a Mailing List Owner") of a mailing list is not set as the envelope sender when processing a `:include:`.
DNS | When making DNS lookups, RES_DNSRCH (search subdomains) and RES_DEFNAMES (append the local domain) are automatically disabled.
aliases | Duplicate left-hand side entries in the aliases(5) file are silently ignored.
`K` | The `K` configuration command (see Section 33.3, "The K Configuration Command") is disabled.
VRFY | The VRFY and EXPN SMTP commands (see Section 22.3.2, "SMTP vrfy and expn") provide the same information. That is, they both act like EXPN.
`F=g` | The `F=g` delivery agent flag (see Section 30.8.22, F=g) cannot be turned off, even if it is omitted. That is, the special address `<>` is never used as the sender of bounced mail.
shells | A user with any shell is allowed to redirect mail to programs or files (see Section 22.8.4, "The /etc/shells file" for how this differs from current behavior).

Note that V1/Sun should be added to your old configuration file only after you have upgraded to Solaris 2.4 or higher's version of sendmail. The `V` configuration command will not be recognized by earlier versions of sendmail, and that command can cause those earlier versions to fail.

D.1 Sun Enhancements |  | D.3 K Command's -d switch