tidying

[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 dbd57d698cac6b6af0cdd0164c3e37a61ce237a6..a73007700e6aebb45834ad2c9d63a309d541fecf 100644 (file)
--- a/doc/doc-txt/experimental-spec.txt
+++ b/doc/doc-txt/experimental-spec.txt
@@ -498,6 +498,8 @@ Enable using EXPERIMENTAL_ARC=yes in your Local/Makefile.
 You must also have DKIM present (not disabled), and you very likely
 want to have SPF enabled.
 
+It is possible to build as a dynamic-load module: set also SUPPORT_ARC=2.
+
 
 Verification
 --
@@ -513,7 +515,9 @@ standard header.
   add_header = :at_start:${authresults {<admd-identifier>}}
 
        Note that it would be wise to strip incoming messages of A-R headers
-       that claim to be from our own <admd-identifier>.
+       that claim to be from our own <admd-identifier>.  Eg:
+
+  remove_header = \N^(?i)Authentication-Results\s*::\s*example.org;\N
 
 There are four new variables:
 
@@ -614,7 +618,7 @@ and a whitespace-separated port number must be given.
 Logging protocol unusual states
 ---------------------------------------------------------------
 An extra log_selector, "protocol_detail" has been added in the default build.
-The name may change in future, hence the Experimenal status.
+The name may change in future, hence the Experimental status.
 
 Currrently the only effect is to enable logging, under TLS,
 of a TCP RST received directly after a QUIT (in server mode).
@@ -626,38 +630,37 @@ being logged.
 
 
 
-Limits ESMTP extension
+XCLIENT proxy support
 ---------------------------------------------------------------
-Per https://datatracker.ietf.org/doc/html/draft-freed-smtp-limits-01
-
-If compiled with EXPERIMENTAL_ESMTP_LIMITS=yes :-
-
-As a server, Exim will advertise, in the EHLO response, the limit for RCPT
-commands set by the recipients_max main-section config option (if it is set),
-and the limit for MAIL commands set by the smtp_accept_max_per_connection
-option.
+Per https://www.postfix.org/XCLIENT_README.html
 
-Note that as of writing, smtp_accept_max_per_connection is expanded but
-recipients_max is not.
+XCLIENT is an ESMTP extension supporting an inbound proxy.
+The only client immplementation known is in Nginx
+(https://nginx.org/en/docs/mail/ngx_mail_proxy_module.html)
 
-A new main-section option "limits_advertise_hosts" controls whether
-the limits are advertised; the default for the option is "*".
+If compiled with EXPERIMENTAL_XCLIENT=yes :-
 
-As a client, Exim will:
+As a server, Exim will advertise XCLIENT support (conditional on a new option
+"hosts_xclient") and service XCLIENT commands with parameters
+  ADDR
+  NAME
+  PORT
+  LOGIN
+  DESTADDR
+  DESTPORT
+A fresh HELO/EHLO is required after a succesful XCLIENT, and the usual
+values are derived from that (making the HELO and PROTO paramemters redundant).
 
- - note an advertised MAILMAX; the lower of the value given and the
- value from the transport connection_max_messages option is used.
+An XCLIENT command must give both ADDR and PORT parameters if no previous
+XCLIENT has succeeded in the SMTP session.
 
- - note an advertised RCPTMAX; the lower of the
- value given and the value from the transport max_rcpt option is used.
- Parallisation of transactions is not done if due to a RCPTMAX, unlike
- max_rcpt.
+After a success:
+  $proxy_session variable becomes "yes"
+  $proxy_local_address, $proxy_local_port have the proxy "inside" values
+  $proxy_external_address, $proxy_external_port have the proxy "outside" values
+  $sender_host_address, $sender_host_port have the remot client values
 
- - note an advertised RCPTDOMAINMAX, and behave as if the transport
- multi_domains option was set to false.  The value advertised is ignored.
 
-Values advertised are only noted for TLS connections and ones for which
-the server does not advertise TLS support.
 
 
 --------------------------------------------------------------