diff --git a/smtprelay.ini b/smtprelay.ini
index 0b97399..d0f3d4e 100644
--- a/smtprelay.ini
+++ b/smtprelay.ini
@@ -35,10 +35,12 @@
 ;allowed_nets = 127.0.0.0/8 ::1/128
 
 ; Regular expression for valid FROM EMail addresses
+; If set to "", then any sender is permitted.
 ; Example: ^(.*)@localhost.localdomain$
 ;allowed_sender =
 
 ; Regular expression for valid TO EMail addresses
+; If set to "", then any recipient is permitted.
 ; Example: ^(.*)@localhost.localdomain$
 ;allowed_recipients =