diff --git a/README.rst b/README.rst
index 71cd68b..61ce1c0 100644
--- a/README.rst
+++ b/README.rst
@@ -23,3 +23,10 @@ By default, the following components are installed:
 * Postfix
 * Dovecot
 * Amavis (with SpamAssassin and ClamAV)  
+
+If you want to follow details of installation process, use --debug
+
+At the end of the process, you should consider updating virus database with this command:: 
+
+  freshclam
+  /etc/init.d/clamav-daemon restart
diff --git a/installer.cfg b/installer.cfg
index b415532..0b181d6 100644
--- a/installer.cfg
+++ b/installer.cfg
@@ -5,6 +5,7 @@ tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
 [database]
 # Select database engine : postgres or mysql
 engine = postgres
+#engine = mysql
 host = 127.0.0.1
 install = true
 
diff --git a/modoboa_installer/database.py b/modoboa_installer/database.py
index eddc7b3..f325617 100644
--- a/modoboa_installer/database.py
+++ b/modoboa_installer/database.py
@@ -45,6 +45,7 @@ class PostgreSQL(Database):
         """Exec a postgresql query."""
         cmd = "psql"
         if dbname and dbuser:
+            self._setup_pgpass(dbname, dbuser, dbpassword)
             cmd += " -h {} -d {} -U {} -w".format(self.dbhost, dbname, dbuser)
         utils.exec_cmd(
             """{} -c "{}" """.format(cmd, query), sudo_user=self.dbuser)
diff --git a/modoboa_installer/scripts/modoboa.py b/modoboa_installer/scripts/modoboa.py
index 59e0f45..145ea51 100644
--- a/modoboa_installer/scripts/modoboa.py
+++ b/modoboa_installer/scripts/modoboa.py
@@ -104,7 +104,8 @@ class Modoboa(base.Installer):
                 "INSERT INTO lib_parameter (name, value) VALUES ('{0}', '{1}')"
                 .format(name, value)
             )
-            self.backend._exec_query(query, self.dbname, self.dbuser)
+            self.backend._exec_query(
+                query, self.dbname, self.dbuser, self.dbpasswd)
 
     def post_run(self):
         """Additional tasks."""
diff --git a/modoboa_installer/scripts/postfix.py b/modoboa_installer/scripts/postfix.py
index 35746d0..382a19f 100644
--- a/modoboa_installer/scripts/postfix.py
+++ b/modoboa_installer/scripts/postfix.py
@@ -48,8 +48,14 @@ class Postfix(base.Installer):
             self.dbengine, self.config.get("modoboa", "dbuser"),
             self.config.get("modoboa", "dbpassword"),
             self.dbhost, self.config.get("modoboa", "dbname"))
+        extensions = self.config.get("modoboa", "extensions")
+        exts_with_maps = ["modoboa-admin", "modoboa-admin-relaydomains",
+                          "modoboa-postfix-autoreply"]
+        extensions = [ext for ext in exts_with_maps if ext in extensions]
+        if not extensions:
+            return
         cmd = (
-            "{} {} postfix_maps --dbtype {} --extensions all --dburl {} {}"
-            .format(python_path, script_path, self.dbengine, db_url,
-                    self.config_dir))
+            "{} {} postfix_maps --dbtype {} --extensions {} --dburl {} {}"
+            .format(python_path, script_path, self.dbengine,
+                    " ".join(extensions), db_url, self.config_dir))
         utils.exec_cmd(cmd)