Docs: add note on costs of cutthrough delivery in local-rejection cases

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

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 18d67fe208458ee87a09ad693f8076fedece0bb0..b413791d5b1f16be534d61b0b5cb12a2292d9bc2 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -9677,7 +9677,8 @@ ${readsocket{inet:[::1]:1234}{request string}}
 Only a single host name may be given, but if looking it up yields more than
 one IP address, they are each tried in turn until a connection is made. For
 both kinds of socket, Exim makes a connection, writes the request string
-(unless it is an empty string) and reads from the socket until an end-of-file
+unless it is an empty string; and no terminating NUL is ever sent)
+and reads from the socket until an end-of-file
 is read. A timeout of 5 seconds is applied. Additional, optional arguments
 extend what can be done. Firstly, you can vary the timeout. For example:
 .code
@@ -23417,6 +23418,15 @@ the message. As a result, the overall timeout for a message depends on the size
 of the message. Its value must not be zero. See also &%final_timeout%&.
 
 
+.option dkim_domain smtp string&!! unset
+.option dkim_selector smtp string&!! unset
+.option dkim_private_key smtp string&!! unset
+.option dkim_canon smtp string&!! unset
+.option dkim_strict smtp string&!! unset
+.option dkim_sign_headers smtp string&!! unset
+DKIM signing options.  For details see &<<SECDKIMSIGN>>&.
+
+
 .option delay_after_cutoff smtp boolean true
 This option controls what happens when all remote IP addresses for a given
 domain have been inaccessible for so long that they have passed their retry
@@ -28607,6 +28617,14 @@ Note also that headers cannot be
 modified by any of the post-data ACLs (DATA, MIME and DKIM).
 Headers may be modified by routers (subject to the above) and transports.
 
+.new
+All the usual ACLs are called; if one results in the message being
+rejected, all effort spent in delivery (including the costs on
+the ultimate destination) will be wasted.
+Note that in the case of data-time ACLs this includes the entire
+message body.
+.wen
+
 Cutthrough delivery is not supported via transport-filters or when DKIM signing
 of outgoing messages is done, because it sends data to the ultimate destination
 before the entire message has been received from the source.
@@ -38005,7 +38023,7 @@ where you accept mail from relay sources (internal hosts or authenticated
 senders).
 
 
-.section "Signing outgoing messages" "SECID513"
+.section "Signing outgoing messages" "SECDKIMSIGN"
 .cindex "DKIM" "signing"
 
 Signing is implemented by setting private options on the SMTP transport.