--- a/xml/en/docs/mail/ngx_mail_core_module.xml
+++ b/xml/en/docs/mail/ngx_mail_core_module.xml
@@ -10,7 +10,7 @@
 <module name="Module ngx_mail_core_module"
         link="/en/docs/mail/ngx_mail_core_module.html"
         lang="en"
-        rev="12">
+        rev="13">
 
 <section id="summary">
 
@@ -285,6 +285,7 @@ parameters <literal>--without-mail_imap_
 <syntax>
     <value>address</value> ...
     [<literal>valid</literal>=<value>time</value>]
+    [<literal>ipv6</literal>=<literal>on</literal>|<literal>off</literal>]
     [<literal>status_zone</literal>=<value>zone</value>]</syntax>
 <syntax><literal>off</literal></syntax>
 <default>off</default>
@@ -313,6 +314,16 @@ starting from versions 1.3.1 and 1.2.2.
 </note>
 </para>
 
+<para id="resolver_ipv6">
+By default, nginx will look up both IPv4 and IPv6 addresses while resolving.
+If looking up of IPv6 addresses is not desired,
+the <literal>ipv6=off</literal> parameter can be specified.
+<note>
+Resolving of names into IPv6 addresses is supported
+starting from version 1.5.8.
+</note>
+</para>
+
 <para id="resolver_valid">
 By default, nginx caches answers using the TTL value of a response.
 An optional <literal>valid</literal> parameter allows overriding it: