Clarify explanation slightly

config/conf.pl

@@ -2588,15 +2588,15 @@ sub command311 {
 
 sub command311b {
     print "$NRM";
-    print "\n  SquirrelMail adds username information to every outgoing
-  email in order to prevent possible sender forging when users are
-  allowed to change their email and/or full name.
+    print "\n  SquirrelMail adds username information to every outgoing email in
+  order to prevent possible sender forging by users that are allowed
+  to change their email and/or full name.
 
   You can remove user information from this header (y) if you think that
   it violates privacy or security.
 
-  Note: If users are allowed to change their email addresses,
-  this setting will make it difficult to determine who sent what where.
+  Note: If users are allowed to change their email addresses, this
+  setting will make it difficult to determine who sent what where.
   Use at your own risk.
 
   Note: If you have defined a header encryption key in your SMTP or