diff -ur man-pages-3.42.orig/man5/nsswitch.conf.5 man-pages-3.42/man5/nsswitch.conf.5
--- man-pages-3.42.orig/man5/nsswitch.conf.5	2012-08-14 00:39:40.000000000 +0200
+++ man-pages-3.42/man5/nsswitch.conf.5	2012-09-13 18:22:52.679702505 +0200
@@ -45,6 +45,11 @@
 Mail aliases, used by
 .BR getaliasent (3)
 and related functions.
+It provides a system-wide mechanism to redirect mail for local
+recipients. Used by mail transfer agents such as Postfix or
+.BR sendmail (8).
+Note: On Linux, not like on other Unices, Sendmail uses its own aliases
+resolution system independent on `/etc/nsswitch.conf'.
 .TP
 .B ethers
 Ethernet numbers.