-# If you uncomment the following line, only root may use the -C or -D options
-# without losing root privilege. The -C option specifies an alternate runtime
-# configuration file, and the -D option changes macro values in the runtime
-# configuration. Uncommenting this line restricts what can be done with these
-# options. A call to receive a message (either one-off or via a daemon) cannot
-# successfully continue to deliver it, because the re-exec of Exim to regain
-# root privilege will fail, owing to the use of -C or -D by the Exim user.
-# However, you can still use -C for testing (as root) if you do separate Exim
-# calls for receiving a message and subsequently delivering it.
+# When a user other than root uses the -C option to override the configuration
+# file (including the Exim user when re-executing Exim to regain root
+# privileges for local message delivery), this will normally cause Exim to
+# drop root privileges. The TRUSTED_CONFIG_PREFIX_LIST option, specifies
+# a file which contains a list of trusted configuration prefixes (like the
+# ALT_CONFIG_PREFIX above), one per line. If the -C option is used to specify
+# a configuration file which matches a trusted prefix, root privileges are not
+# dropped by Exim.