diff --git a/install/lib/installer_base.lib.php b/install/lib/installer_base.lib.php
index 51eaa387989d1fa29aac6845922be76f223ce161..1bffeb8e8a541b641472f8cd9c02387125c38c9e 100644
--- a/install/lib/installer_base.lib.php
+++ b/install/lib/installer_base.lib.php
@@ -209,6 +209,9 @@ class installer_base {
 
 		//* mysql-virtual_client.cf
         $this->process_postfix_config('mysql-virtual_client.cf');
+		
+		//* mysql-virtual_relaydomains.cf
+        $this->process_postfix_config('mysql-virtual_relaydomains.cf');
 
 		//* Changing mode and group of the new created config files.
 		caselog('chmod o= '.$config_dir.'/mysql-virtual_*.cf* &> /dev/null',
@@ -241,6 +244,7 @@ class installer_base {
 			'smtpd_tls_cert_file = '.$config_dir.'/smtpd.cert',
 			'smtpd_tls_key_file = '.$config_dir.'/smtpd.key',
 			'transport_maps = proxy:mysql:'.$config_dir.'/mysql-virtual_transports.cf',
+			'relay_domains = mysql:'.$config_dir.'/mysql-virtual_relaydomains.cf',
 			'virtual_create_maildirsize = yes',
 			'virtual_mailbox_extended = yes',
 			'virtual_mailbox_limit_maps = proxy:mysql:'.$config_dir.'/mysql-virtual_mailbox_limit_maps.cf',
diff --git a/install/tpl/mysql-virtual_relaydomains.cf.master b/install/tpl/mysql-virtual_relaydomains.cf.master
new file mode 100644
index 0000000000000000000000000000000000000000..fb7bec1a3a60d53ee9103f0a8bb32cc280bc8797
--- /dev/null
+++ b/install/tpl/mysql-virtual_relaydomains.cf.master
@@ -0,0 +1,8 @@
+user = {mysql_server_ispconfig_user}
+password = {mysql_server_ispconfig_password}
+dbname = {mysql_server_database}
+table = mail_transport
+select_field = domain
+where_field = domain
+additional_conditions = and active = 'y' and server_id = {server_id}
+hosts = {mysql_server_ip}
\ No newline at end of file