main: add missing host_lookup_order option (set to default value)

1 files changed, 14 insertions, 0 deletions

diff --git a/conf.d/010_main.conf b/conf.d/010_main.conf
index 7fc96ef..b04e9f5 100644
--- a/conf.d/010_main.conf
+++ b/conf.d/010_main.conf
@@ -128,6 +128,20 @@ never_users = root
 host_lookup = *
 
 
+# This option specifies the order of different lookup methods when Exim is
+# trying to find a host name from an IP address. The default is to do a DNS
+# lookup first, and then to try a local lookup (using gethostbyaddr() or
+# equivalent) if that fails. You can change the order of these lookups, or omit
+# one entirely, if you want.
+#
+# Warning: The “byaddr” method does not always yield aliases when there are
+# multiple PTR records in the DNS and the IP address is not listed in
+# /etc/hosts. Different operating systems give different results in this case.
+# That is why the default tries a DNS lookup first.
+
+#host_lookup_order = bydns : byaddr
+
+
 # The settings below cause Exim to make RFC 1413 (ident) callbacks
 # for all incoming SMTP calls. You can limit the hosts to which these
 # calls are made, and/or change the timeout that is used. If you set