diff --git a/etc/mail/aliases b/etc/mail/aliases
index 682f878f53a8..ae0e7f1c3fbd 100644
--- a/etc/mail/aliases
+++ b/etc/mail/aliases
@@ -11,6 +11,7 @@
 #
 # See also RFC 2142, `MAILBOX NAMES FOR COMMON SERVICES, ROLES
 # AND FUNCTIONS', May 1997
+# 	http://tools.ietf.org/html/rfc2142
 
 # Pretty much everything else in this file points to "root", so
 # you would do well in either reading root's mailbox or forwarding