masquerading (wouldn't want sysadmins to not realize that by allowing one,
they're allowing the other). I also prefer my new wording of "allow" vs. the
old "turn on" because the latter implied that masquerading would take effect
just by setting that variable (not the case unless /etc/passwd had been
previously modified to have the <fakeusername>s).
# query the system for this value (gethostname, etc...).
# localname: foo.bar.com
-# Uncomment this to turn on username masquerading.
+# Uncomment this to allow the two types of username masquerading.
# mmailid: 1