Callouts: a "hold" option for receipient-verify, which keeps the connection open...

[exim.git] / doc / doc-docbook / spec.xfpt

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 128ee8004002062b88476fe64b63b6a5e715c2a1..925b96324bd4d8c373376523e91f7fe683fa71d4 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -3869,12 +3869,12 @@ by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
 host to which Exim is connected supports TLS encryption.
 
 .new
-.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>
+.vitem &%-MCt%&&~<&'IP&~address'&>&~<&'port'&>&~<&'cipher'&>
 .oindex "&%-MCt%&"
 This option is not intended for use by external callers. It is used internally
 by Exim in conjunction with the &%-MC%& option, and passes on the fact that the
 connection is being proxied by a parent process for handling TLS encryption.
-The pair of arguments give the local address and port being proxied.
+The arguments give the local address and port being proxied, and the TLS cipher.
 .wen
 
 .vitem &%-Mc%&&~<&'message&~id'&>&~<&'message&~id'&>&~...
@@ -30908,6 +30908,21 @@ command when performing the callout, instead of an empty address. There is no
 need to use this option unless you know that the called hosts make use of the
 sender when checking recipients. If used indiscriminately, it reduces the
 usefulness of callout caching.
+
+.vitem &*hold*&
+This option applies to recipient callouts only. For example:
+.code
+require  verify = recipient/callout=use_sender,hold
+.endd
+It causes the connection to be helod open and used for any further recipients
+and for eventual delivery (should that be done quickly).
+Doing this saves on TCP and SMTP startup costs, and TLS costs also
+when that is used for the connections.
+The advantage is only gained if there are no callout cache hits
+(which could be enforced by the no_cache option),
+if the use_sender option is used,
+if neither the random nor the use_postmaster option is used,
+and if no other callouts intervene.
 .endlist
 
 If you use any of the parameters that set a non-empty sender for the MAIL
@@ -35774,10 +35789,9 @@ down a single SMTP connection, an asterisk follows the IP address in the log
 lines for the second and subsequent messages.
 .new
 When two or more messages are delivered down a single TLS connection, the
-DNS and TLS-related information logged for the first message delivered
+DNS and some TLS-related information logged for the first message delivered
 will not be present in the log lines for the second and subsequent messages.
-A TLS-marker indication of &'X=*'& is added to the log line instead of
-cipher information.
+TLS cipher information is still available.
 .wen
 
 .cindex "delivery" "cutthrough; logging"
@@ -35906,7 +35920,7 @@ the following table:
 &`T   `&        on &`<=`& lines: message subject (topic)
 &`    `&        on &`=>`& &`**`& and &`==`& lines: transport name
 &`U   `&        local user or RFC 1413 identity
-&`X   `&        TLS cipher suite, or TLS usage mark
+&`X   `&        TLS cipher suite
 .endd