diff --git a/man/login.defs.d/MAIL_DIR.xml b/man/login.defs.d/MAIL_DIR.xml
index 60b82d6b..b5adb888 100644
--- a/man/login.defs.d/MAIL_DIR.xml
+++ b/man/login.defs.d/MAIL_DIR.xml
@@ -35,6 +35,8 @@
       The mail spool directory. This is needed to manipulate the mailbox
       when its corresponding user account is modified or deleted. If not
       specified, a compile-time default is used.
+      The parameter CREATE_MAIL_SPOOL in <filename>/etc/default/useradd</filename>
+      determines whether the mail spool should be created.
     </para>
   </listitem>
 </varlistentry><varlistentry>