Rename dns_use_dnssec to dns_dnssec_ok.

[exim.git] / doc / doc-txt / experimental-spec.txt

diff --git a/doc/doc-txt/experimental-spec.txt b/doc/doc-txt/experimental-spec.txt
index 7bb17883c77143434880f96872197045d72b3a00..8d1ebef13b227d987dabb449566a93aa75c71383 100644 (file)
--- a/doc/doc-txt/experimental-spec.txt
+++ b/doc/doc-txt/experimental-spec.txt
@@ -6,6 +6,34 @@ about experimental  features, all  of which  are unstable and
 liable to incompatible change.
 
 
 liable to incompatible change.
 
 

+PRDR support
+--------------------------------------------------------------
+
+Per-Recipient Data Reponse is an SMTP extension proposed by Eric Hall
+in a (now-expired) IETF draft from 2007.  It's not hit mainstream
+use, but has apparently been implemented in the META1 MTA.
+
+There is mention at http://mail.aegee.org/intern/sendmail.html
+of a patch to sendmail "to make it PRDR capable".
+
+ ref: http://www.eric-a-hall.com/specs/draft-hall-prdr-00.txt
+
+If Exim is built with EXPERIMENTAL_PRDR there is a new config
+boolean "prdr_enable" which controls whether PRDR is advertised
+as part of an EHLO response, a new "acl_data_smtp_prdr" ACL
+(called for each recipient, after data arrives but before the
+data ACL), and a new smtp transport option "hosts_try_prdr".
+
+PRDR may be used to support per-user content filtering.  Without it
+one must defer any recipient after the first that has a different
+content-filter configuration.  With PRDR, the RCPT-time check
+for this can be disabled when the MAIL-time $smtp_command included
+"PRDR".  Any required difference in behaviour of the main DATA-time
+ACL should however depend on the PRDR-time ACL having run, as Exim
+will avoid doing so in some situations (eg.  single-recipient mails).
+
+
+

 OCSP Stapling support
 --------------------------------------------------------------
 
 OCSP Stapling support
 --------------------------------------------------------------
 


@@ -570,10 +598,29 @@ through to eg. SpamAssassin.
 If you want to pass even more headers in the middle of the
 DATA stage you can set
   $acl_m_dcc_add_header
 If you want to pass even more headers in the middle of the
 DATA stage you can set
   $acl_m_dcc_add_header

-to tell the DCC routines add more information; eg, you might set
+to tell the DCC routines to add more information; eg, you might set

 this to some results from ClamAV.  Be careful.  Header syntax is
 not checked and is added "as is".
 
 this to some results from ClamAV.  Be careful.  Header syntax is
 not checked and is added "as is".
 

+In case you've troubles with sites sending the same queue items from several
+hosts and fail to get through greylisting you can use
+$acl_m_dcc_override_client_ip
+
+Setting $acl_m_dcc_override_client_ip to an IP address overrides the default
+of $sender_host_address. eg. use the following ACL in DATA stage:
+
+  warn    set acl_m_dcc_override_client_ip = \
+    ${lookup{$sender_helo_name}nwildlsearch{/etc/mail/multipleip_sites}{$value}{}}
+          condition = ${if def:acl_m_dcc_override_client_ip}
+          log_message = dbg: acl_m_dcc_override_client_ip set to \
+                        $acl_m_dcc_override_client_ip
+
+Then set something like
+# cat /etc/mail/multipleip_sites
+mout-xforward.gmx.net           82.165.159.12
+mout.gmx.net                    212.227.15.16
+
+Use a reasonable IP. eg. one the sending cluster acutally uses.

 
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