diff --git a/DOCUMENTS/Postfix-Dovecot-Postgresql-Example.md b/DOCUMENTS/Postfix-Dovecot-Postgresql-Example.md
index 7d41296a..1e113faa 100644
--- a/DOCUMENTS/Postfix-Dovecot-Postgresql-Example.md
+++ b/DOCUMENTS/Postfix-Dovecot-Postgresql-Example.md
@@ -32,6 +32,7 @@ virtual_uid_maps = static:8
 virtual_gid_maps = static:8
 local_transport = virtual
 local_recipient_maps = $virtual_mailbox_maps
+smtpd_sender_login_maps = proxy:pgsql:/etc/postfix/pgsql/virtual_sender_maps.cf
 ```
 
 and for Postfix SASL support :
@@ -46,6 +47,12 @@ smtpd_sasl_security_options = noanonymous
 broken_sasl_auth_clients = yes
 ```
 
+Please note that `smtpd_sender_login_maps` is only taken into account when a relevant restriction is specified in `smtpd_sender_restrictions`.
+
+By default a client can send emails from any addresses!
+
+For reference: http://www.postfix.org/postconf.5.html#reject_sender_login_mismatch
+
 ## /etc/postfix/pgsql/relay_domains.cf
 
 ```
@@ -99,6 +106,16 @@ dbname = postfix
 query = SELECT maildir FROM mailbox WHERE username='%s' AND active = true
 ```
 
+## /etc/postfix/pgsql/virtual_sender_maps.cf
+
+```
+user = postfix
+password = whatever
+hosts = localhost
+dbname = postfix
+query = SELECT username FROM mailbox WHERE username='%s' AND active = true
+```
+
 
 # Dovecot