It is permitted to specify a space as the separator character. Further
white space is ignored.
+.section "Dnsdb lookup modifiers" "SECTdnsdb_mod"
+.cindex "dnsdb modifiers"
+.cindex "modifiers" "dnsdb"
+.cindex "options" "dnsdb"
+Modifiers for &(dnsdb)& lookups are givien by optional keywords,
+each followed by a comma,
+that may appear before the record type.
+
+The &(dnsdb)& lookup fails only if all the DNS lookups fail. If there is a
+temporary DNS error for any of them, the behaviour is controlled by
+a defer-option modifier.
+The possible keywords are
+&"defer_strict"&, &"defer_never"&, and &"defer_lax"&.
+With &"strict"& behaviour, any temporary DNS error causes the
+whole lookup to defer. With &"never"& behaviour, a temporary DNS error is
+ignored, and the behaviour is as if the DNS lookup failed to find anything.
+With &"lax"& behaviour, all the queries are attempted, but a temporary DNS
+error causes the whole lookup to defer only if none of the other lookups
+succeed. The default is &"lax"&, so the following lookups are equivalent:
+.code
+${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}}
+${lookup dnsdb{a=one.host.com:two.host.com}}
+.endd
+Thus, in the default case, as long as at least one of the DNS lookups
+yields some data, the lookup succeeds.
+
+.cindex "DNSSEC" "dns lookup"
+Use of &(DNSSEC)& is controlled by a dnssec modifier.
+The possible keywords are
+&"dnssec_strict"&, &"dnssec_lax"&, and &"dnssec_never"&.
+With &"strict"& or &"lax"& DNSSEC information is requested
+with the lookup.
+With &"strict"& a response from the DNS resolver that
+is not labelled as authenticated data
+is treated as equivalent to a temporary DNS error.
+The default is &"never"&.
+
+See also the &$lookup_dnssec_authenticated$& variable.
+
+
.section "Pseudo dnsdb record types" "SECID66"
.cindex "MX record" "in &(dnsdb)& lookup"
By default, both the preference value and the host name are returned for
in the same way that multiple DNS records for a single item are handled. A
different separator can be specified, as described above.
-Modifiers for &(dnsdb)& lookups are givien by optional keywords,
-each followed by a comma,
-that may appear before the record type.
-
-The &(dnsdb)& lookup fails only if all the DNS lookups fail. If there is a
-temporary DNS error for any of them, the behaviour is controlled by
-a defer-option modifier.
-The possible keywords are
-&"defer_strict"&, &"defer_never"&, and &"defer_lax"&.
-With &"strict"& behaviour, any temporary DNS error causes the
-whole lookup to defer. With &"never"& behaviour, a temporary DNS error is
-ignored, and the behaviour is as if the DNS lookup failed to find anything.
-With &"lax"& behaviour, all the queries are attempted, but a temporary DNS
-error causes the whole lookup to defer only if none of the other lookups
-succeed. The default is &"lax"&, so the following lookups are equivalent:
-.code
-${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}}
-${lookup dnsdb{a=one.host.com:two.host.com}}
-.endd
-Thus, in the default case, as long as at least one of the DNS lookups
-yields some data, the lookup succeeds.
-
-.cindex "DNSSEC" "dns lookup"
-Use of &(DNSSEC)& is controlled by a dnssec modifier.
-The possible keywords are
-&"dnssec_strict"&, &"dnssec_lax"&, and &"dnssec_never"&.
-With &"strict"& or &"lax"& DNSSEC information is requested
-with the lookup.
-With &"strict"& a response from the DNS resolver that
-is not labelled as authenticated data
-is treated as equivalent to a temporary DNS error.
-The default is &"never"&.
-
-See also the &$lookup_dnssec_authenticated$& variable.
-
.cindex "expansion" "inserting from a socket"
.cindex "socket, use of in expansion"
.cindex "&%readsocket%& expansion item"
-This item inserts data from a Unix domain or Internet socket into the expanded
+This item inserts data from a Unix domain or TCP socket into the expanded
string. The minimal way of using it uses just two arguments, as in these
examples:
.code
.cindex "&ACL;" "cutthrough routing"
.cindex "cutthrough" "requesting"
This option requests delivery be attempted while the item is being received.
-It is usable in the RCPT ACL and valid only for single-recipient mails forwarded
-from one SMTP connection to another. If a recipient-verify callout connection is
-requested in the same ACL it is held open and used for the data, otherwise one is made
-after the ACL completes.
+
+The option usable in the RCPT ACL.
+If enabled for a message recieved via smtp and routed to an smtp transport,
+and the message has only one recipient,
+then the delivery connection is made while the receiving connection is open
+and data is copied from one to the other.
+
+If a recipient-verify callout connection is subsequently
+requested in the same ACL it is held open and used for the data,
+otherwise one is made after the initial RCPT ACL completes.
Note that routers are used in verify mode,
and cannot depend on content of received headers.
Should the ultimate destination system positively accept or reject the mail,
a corresponding indication is given to the source system and nothing is queued.
If there is a temporary error the item is queued for later delivery in the
-usual fashion. If the item is successfully delivered in cutthrough mode the log line
-is tagged with ">>" rather than "=>" and appears before the acceptance "<="
-line.
+usual fashion. If the item is successfully delivered in cutthrough mode
+the log line is tagged with ">>" rather than "=>" and appears
+before the acceptance "<=" line.
-Delivery in this mode avoids the generation of a bounce mail to a (possibly faked)
+Delivery in this mode avoids the generation of a bounce mail to a
+(possibly faked)
sender when the destination system is doing content-scan based rejection.
git://git.exim.org / exim.git / blobdiff