Rule sets in the configuration file, like subroutines in a program,
control the sequence of steps sendmail uses to
rewrite addresses. Inside each
rule set is a series of zero or more individual rules. Rules are used
to select the appropriate delivery agent for any particular address,
to detect and reject addressing errors, to transform addresses to
meet particular needs, to validate addresses and headers for the
purpose of rejecting spam, and to make policy decisions.
V8.13 has introduced one change in rule sets:
New character commands were added to the
svr_featuresrule set (Section 19.1.1 [V8.13]).
The svr_features rule set
(19.1.3[3ed]) returns a
$# followed by one or more of the characters
defined in Table 19-1. Each
character turns a feature on or off. If
the character is lowercase, it turns the feature on. Uppercase turns
the feature off. One character, the t, is special
because it causes sendmail to temporarily fail
the connection. Prior to V8.13, the characters listed in the table
below (as documented in V8.13) were undocumented (and thus
unsupported). They are now both documented and
supported.
Table 19-1. Characters that set/clear server features
|
On |
Off |
Documented |
Description |
|---|---|---|---|
|
|
|
V8.12 |
Offer the AUTH SMTP extension |
|
|
|
V8.13 |
Offer use of the SMTP VERB command |
|
c |
C |
V8.12 |
“C” is the equivalent to
|
|
|
|
V8.13 |
Offer the DSN SMTP extension |
|
|
|
V8.13 |
Offer the ETRN SMTP extension |
|
|
|
V8.13 |
Require the client to authenticate with AUTH |
|
|
|
V8.12 |
Offer the PIPELINING SMTP extension |
|
r |
R |
V8.13 |
Request a certificate |
|
|
|
V8.12 |
Offer the STARTTLS SMTP extension |
|
|
|
V8.12 |
Verify a client certificate |
|
|
|
V8.13 |
Offer use of the SMTP EXPN command |