diff --git a/modoboa_installer/database.py b/modoboa_installer/database.py
index bb0ec2c..0242800 100644
--- a/modoboa_installer/database.py
+++ b/modoboa_installer/database.py
@@ -13,6 +13,7 @@ class Database(object):
 
     """Common database backend."""
 
+    default_port = None
     packages = None
     service = None
 
@@ -21,6 +22,8 @@ class Database(object):
         self.config = config
         engine = self.config.get("database", "engine")
         self.dbhost = self.config.get("database", "host")
+        self.dbport = self.config.getint(
+            "database", "port", fallback=self.default_port)
         self.dbuser = config.get(engine, "user")
         self.dbpassword = config.get(engine, "password")
         if self.config.getboolean("database", "install"):
@@ -36,6 +39,7 @@ class PostgreSQL(Database):
 
     """Postgres."""
 
+    default_port = 5432
     packages = {
         "deb": ["postgresql", "postgresql-server-dev-all"],
         "rpm": ["postgresql-server", "postgresql-devel"]
@@ -43,7 +47,7 @@ class PostgreSQL(Database):
     service = "postgresql"
 
     def __init__(self, config):
-        super(PostgreSQL, self).__init__(config)
+        super().__init__(config)
         self._pgpass_done = False
 
     def install_package(self):
@@ -79,7 +83,8 @@ class PostgreSQL(Database):
             cmd += " -d {}".format(dbname)
             if dbuser:
                 self._setup_pgpass(dbname, dbuser, dbpassword)
-                cmd += " -h {} -U {} -w".format(self.dbhost, dbuser)
+                cmd += " -h {} -p {} -U {} -w".format(
+                    self.dbhost, self.dbport, dbuser)
         query = query.replace("'", "'\"'\"'")
         cmd = "{} -c '{}' ".format(cmd, query)
         utils.exec_cmd(cmd, sudo_user=self.dbuser)
@@ -137,8 +142,8 @@ class PostgreSQL(Database):
     def load_sql_file(self, dbname, dbuser, dbpassword, path):
         """Load SQL file."""
         self._setup_pgpass(dbname, dbuser, dbpassword)
-        cmd = "psql -h {} -d {} -U {} -w < {}".format(
-            self.dbhost, dbname, dbuser, path)
+        cmd = "psql -h {} -p {} -d {} -U {} -w < {}".format(
+            self.dbhost, self.dbport, dbname, dbuser, path)
         utils.exec_cmd(cmd, sudo_user=self.dbuser)
 
     def dump_database(self, dbname, dbuser, dbpassword, path):
@@ -155,6 +160,7 @@ class MySQL(Database):
 
     """MySQL backend."""
 
+    default_port = 3306
     packages = {
         "deb": ["mariadb-server"],
         "rpm": ["mariadb", "mariadb-devel", "mariadb-server"],
@@ -211,7 +217,8 @@ class MySQL(Database):
         if dbuser is None and dbpassword is None:
             dbuser = self.dbuser
             dbpassword = self.dbpassword
-        cmd = "mysql -h {} -u {}".format(self.dbhost, dbuser)
+        cmd = "mysql -h {} -P {} -u {}".format(
+            self.dbhost, self.dbport, dbuser)
         if dbpassword:
             cmd += " -p{}".format(dbpassword)
         if dbname:
@@ -256,8 +263,8 @@ class MySQL(Database):
     def load_sql_file(self, dbname, dbuser, dbpassword, path):
         """Load SQL file."""
         utils.exec_cmd(
-            "mysql -h {} -u {} -p{} {} < {}".format(
-                self.dbhost, dbuser, dbpassword, dbname, path)
+            "mysql -h {} -P {} -u {} -p{} {} < {}".format(
+                self.dbhost, self.dbport, dbuser, dbpassword, dbname, path)
         )
 
     def dump_database(self, dbname, dbuser, dbpassword, path):
diff --git a/modoboa_installer/scripts/automx.py b/modoboa_installer/scripts/automx.py
index b086e9e..7b9ed56 100644
--- a/modoboa_installer/scripts/automx.py
+++ b/modoboa_installer/scripts/automx.py
@@ -33,11 +33,12 @@ class Automx(base.Installer):
     def get_template_context(self):
         """Additional variables."""
         context = super(Automx, self).get_template_context()
-        sql_dsn = "{}://{}:{}@{}/{}".format(
+        sql_dsn = "{}://{}:{}@{}:{}/{}".format(
             "postgresql" if self.dbengine == "postgres" else self.dbengine,
             self.config.get("modoboa", "dbuser"),
             self.config.get("modoboa", "dbpassword"),
             self.dbhost,
+            self.dbport,
             self.config.get("modoboa", "dbname"))
         if self.db_driver == "pgsql":
             sql_query = (
diff --git a/modoboa_installer/scripts/base.py b/modoboa_installer/scripts/base.py
index d56fdb0..43e7939 100644
--- a/modoboa_installer/scripts/base.py
+++ b/modoboa_installer/scripts/base.py
@@ -31,7 +31,10 @@ class Installer(object):
         # Used to install system packages
         self.db_driver = (
             "pgsql" if self.dbengine == "postgres" else self.dbengine)
+        self.backend = database.get_backend(self.config)
         self.dbhost = self.config.get("database", "host")
+        self.dbport = self.config.get(
+            "database", "port", fallback=self.backend.default_port)
         self._config_dir = None
         if not self.with_db:
             return
@@ -62,7 +65,6 @@ class Installer(object):
         """Setup a database."""
         if not self.with_db:
             return
-        self.backend = database.get_backend(self.config)
         self.backend.create_user(self.dbuser, self.dbpasswd)
         self.backend.create_database(self.dbname, self.dbuser)
         schema = self.get_sql_schema_path()
@@ -87,6 +89,7 @@ class Installer(object):
             "dbengine": (
                 "Pg" if self.dbengine == "postgres" else self.dbengine),
             "dbhost": self.dbhost,
+            "dbport": self.dbport,
         }
         for option, value in self.config.items("general"):
             context[option] = value
diff --git a/modoboa_installer/scripts/dovecot.py b/modoboa_installer/scripts/dovecot.py
index cc353ed..3bb2518 100644
--- a/modoboa_installer/scripts/dovecot.py
+++ b/modoboa_installer/scripts/dovecot.py
@@ -124,6 +124,12 @@ class Dovecot(base.Installer):
             utils.copy_file(f, "{}/conf.d".format(self.config_dir))
         # Make postlogin script executable
         utils.exec_cmd("chmod +x /usr/local/bin/postlogin.sh")
+        # Add mailboxes user to dovecot group for modoboa mailbox commands.
+        # See https://github.com/modoboa/modoboa/issues/2157.
+        system.add_user_to_group(
+            self.config.get("dovecot", "mailboxes_owner"),
+            'dovecot'
+        )
 
     def restart_daemon(self):
         """Restart daemon process.
diff --git a/modoboa_installer/scripts/files/amavis/amavisd.conf.tpl b/modoboa_installer/scripts/files/amavis/amavisd.conf.tpl
index b29cac2..659d738 100644
--- a/modoboa_installer/scripts/files/amavis/amavisd.conf.tpl
+++ b/modoboa_installer/scripts/files/amavis/amavisd.conf.tpl
@@ -112,7 +112,7 @@ $sa_local_tests_only = 0;    # only tests which do not require internet access?
 # @storage_redis_dsn = ( {server=>'127.0.0.1:6379', db_id=>1} );
 # $redis_logging_key = 'amavis-log';
 # $redis_logging_queue_size_limit = 300000;  # about 250 MB / 100000
-@lookup_sql_dsn = ( [ 'DBI:%dbengine:database=%dbname;host=%dbhost', '%dbuser', '%dbpassword' ]);
+@lookup_sql_dsn = ( [ 'DBI:%dbengine:database=%dbname;host=%dbhost;port=%dbport', '%dbuser', '%dbpassword' ]);
 @storage_sql_dsn = @lookup_sql_dsn;
 $sql_allow_8bit_address = 1;
 
diff --git a/modoboa_installer/scripts/files/amavis/conf.d/50-user.tpl b/modoboa_installer/scripts/files/amavis/conf.d/50-user.tpl
index e1ef878..d6a2370 100644
--- a/modoboa_installer/scripts/files/amavis/conf.d/50-user.tpl
+++ b/modoboa_installer/scripts/files/amavis/conf.d/50-user.tpl
@@ -7,7 +7,7 @@ $max_servers = %max_servers;
 
 # SQL configuration
 #
-@lookup_sql_dsn = ( [ 'DBI:%dbengine:database=%dbname;host=%dbhost', '%dbuser', '%dbpassword' ]);
+@lookup_sql_dsn = ( [ 'DBI:%dbengine:database=%dbname;host=%dbhost;port=%dbport', '%dbuser', '%dbpassword' ]);
 @storage_sql_dsn = @lookup_sql_dsn;
 $sql_allow_8bit_address = 1;
 
diff --git a/modoboa_installer/scripts/files/dovecot/dovecot-dict-sql.conf.ext.tpl b/modoboa_installer/scripts/files/dovecot/dovecot-dict-sql.conf.ext.tpl
index 8221655..aadba2f 100644
--- a/modoboa_installer/scripts/files/dovecot/dovecot-dict-sql.conf.ext.tpl
+++ b/modoboa_installer/scripts/files/dovecot/dovecot-dict-sql.conf.ext.tpl
@@ -1,4 +1,4 @@
-connect = host=%dbhost dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
+connect = host=%dbhost port=%dbport dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
 
 # CREATE TABLE quota (
 #   username varchar(100) not null,
diff --git a/modoboa_installer/scripts/files/dovecot/dovecot-sql-master-mysql.conf.ext.tpl b/modoboa_installer/scripts/files/dovecot/dovecot-sql-master-mysql.conf.ext.tpl
index 353b4e5..cfeabbf 100644
--- a/modoboa_installer/scripts/files/dovecot/dovecot-sql-master-mysql.conf.ext.tpl
+++ b/modoboa_installer/scripts/files/dovecot/dovecot-sql-master-mysql.conf.ext.tpl
@@ -64,7 +64,7 @@ driver = %db_driver
 #   connect = /etc/dovecot/authdb.sqlite
 #
 #connect =
-connect = host=%dbhost dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
+connect = host=%dbhost port=%dbport dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
 
 # Default password scheme.
 #
diff --git a/modoboa_installer/scripts/files/dovecot/dovecot-sql-master-postgres.conf.ext.tpl b/modoboa_installer/scripts/files/dovecot/dovecot-sql-master-postgres.conf.ext.tpl
index 6e12586..03b4995 100644
--- a/modoboa_installer/scripts/files/dovecot/dovecot-sql-master-postgres.conf.ext.tpl
+++ b/modoboa_installer/scripts/files/dovecot/dovecot-sql-master-postgres.conf.ext.tpl
@@ -64,7 +64,7 @@ driver = %db_driver
 #   connect = /etc/dovecot/authdb.sqlite
 #
 #connect =
-connect = host=%dbhost dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
+connect = host=%dbhost port=%dbport dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
 
 # Default password scheme.
 #
diff --git a/modoboa_installer/scripts/files/dovecot/dovecot-sql-mysql.conf.ext.tpl b/modoboa_installer/scripts/files/dovecot/dovecot-sql-mysql.conf.ext.tpl
index 4af0d86..4538b9a 100644
--- a/modoboa_installer/scripts/files/dovecot/dovecot-sql-mysql.conf.ext.tpl
+++ b/modoboa_installer/scripts/files/dovecot/dovecot-sql-mysql.conf.ext.tpl
@@ -64,7 +64,7 @@ driver = %db_driver
 #   connect = /etc/dovecot/authdb.sqlite
 #
 #connect =
-connect = host=%dbhost dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
+connect = host=%dbhost port=%dbport dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
 
 # Default password scheme.
 #
diff --git a/modoboa_installer/scripts/files/dovecot/dovecot-sql-postgres.conf.ext.tpl b/modoboa_installer/scripts/files/dovecot/dovecot-sql-postgres.conf.ext.tpl
index e6328a5..abb5379 100644
--- a/modoboa_installer/scripts/files/dovecot/dovecot-sql-postgres.conf.ext.tpl
+++ b/modoboa_installer/scripts/files/dovecot/dovecot-sql-postgres.conf.ext.tpl
@@ -64,7 +64,7 @@ driver = %db_driver
 #   connect = /etc/dovecot/authdb.sqlite
 #
 #connect =
-connect = host=%dbhost dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
+connect = host=%dbhost port=%dbport dbname=%modoboa_dbname user=%modoboa_dbuser password=%modoboa_dbpassword
 
 # Default password scheme.
 #
diff --git a/modoboa_installer/scripts/files/opendkim/opendkim.conf.tpl b/modoboa_installer/scripts/files/opendkim/opendkim.conf.tpl
index 9f689fc..c38b94c 100644
--- a/modoboa_installer/scripts/files/opendkim/opendkim.conf.tpl
+++ b/modoboa_installer/scripts/files/opendkim/opendkim.conf.tpl
@@ -18,8 +18,8 @@ UMask			007
 #KeyFile		/etc/dkimkeys/dkim.key
 #Selector		2007
 
-KeyTable		dsn:%{db_driver}://%{db_user}:%{db_password}@%{dbhost}/%{db_name}/table=dkim?keycol=id?datacol=domain_name,selector,private_key_path
-SigningTable		dsn:%db_driver://%{db_user}:%{db_password}@%{dbhost}/%{db_name}/table=dkim?keycol=domain_name?datacol=id
+KeyTable		dsn:%{db_driver}://%{db_user}:%{db_password}@%{dbhost}:%{dbport}/%{db_name}/table=dkim?keycol=id?datacol=domain_name,selector,private_key_path
+SigningTable		dsn:%db_driver://%{db_user}:%{db_password}@%{dbhost}:%{dbport}/%{db_name}/table=dkim?keycol=domain_name?datacol=id
 
 # Commonly-used options; the commented-out versions show the defaults.
 #Canonicalization	simple
diff --git a/modoboa_installer/scripts/files/postfix/main.cf.tpl b/modoboa_installer/scripts/files/postfix/main.cf.tpl
index 7af5487..9bc9b44 100644
--- a/modoboa_installer/scripts/files/postfix/main.cf.tpl
+++ b/modoboa_installer/scripts/files/postfix/main.cf.tpl
@@ -3,7 +3,7 @@ inet_protocols = all
 myhostname = %hostname
 myorigin = $myhostname
 mydestination = $myhostname
-mynetworks = 127.0.0.0/8
+mynetworks = 127.0.0.0/8 [::1]/128
 smtpd_banner = $myhostname ESMTP
 biff = no
 unknown_local_recipient_reject_code = 550
@@ -142,10 +142,10 @@ postscreen_blacklist_action = enforce
 
 # Use some DNSBL
 postscreen_dnsbl_sites = 
-	zen.spamhaus.org*3
-	bl.spameatingmonkey.net*2
-	bl.spamcop.net
-	dnsbl.sorbs.net
+	zen.spamhaus.org=127.0.0.[2..11]*3
+	bl.spameatingmonkey.net=127.0.0.2*2
+	bl.spamcop.net=127.0.0.2
+	dnsbl.sorbs.net=127.0.0.[2..15]
 postscreen_dnsbl_threshold = 3 
 postscreen_dnsbl_action = enforce 
 
diff --git a/modoboa_installer/scripts/modoboa.py b/modoboa_installer/scripts/modoboa.py
index d9e7ad0..c14888b 100644
--- a/modoboa_installer/scripts/modoboa.py
+++ b/modoboa_installer/scripts/modoboa.py
@@ -144,20 +144,22 @@ class Modoboa(base.Installer):
             "--domain", self.config.get("general", "hostname"),
             "--extensions", " ".join(self.extensions),
             "--dont-install-extensions",
-            "--dburl", "'default:{}://{}:{}@{}/{}'".format(
+            "--dburl", "'default:{}://{}:{}@{}:{}/{}'".format(
                 self.config.get("database", "engine"),
-                self.dbuser, self.dbpasswd, self.dbhost, self.dbname
+                self.dbuser, self.dbpasswd, self.dbhost, self.dbport,
+                self.dbname
             )
         ]
         if self.devmode:
             args = ["--devel"] + args
         if self.amavis_enabled:
             args += [
-                "'amavis:{}://{}:{}@{}/{}'".format(
+                "'amavis:{}://{}:{}@{}:{}/{}'".format(
                     self.config.get("database", "engine"),
                     self.config.get("amavis", "dbuser"),
                     self.config.get("amavis", "dbpassword"),
                     self.dbhost,
+                    self.dbport,
                     self.config.get("amavis", "dbname")
                 )
             ]
diff --git a/modoboa_installer/scripts/postwhite.py b/modoboa_installer/scripts/postwhite.py
index 040a212..4a36182 100644
--- a/modoboa_installer/scripts/postwhite.py
+++ b/modoboa_installer/scripts/postwhite.py
@@ -20,6 +20,7 @@ class Postwhite(base.Installer):
     ]
     no_daemon = True
     packages = {
+        "deb": ["bind9-host"],
         "rpm": ["bind-utils"]
     }
 
diff --git a/modoboa_installer/scripts/spamassassin.py b/modoboa_installer/scripts/spamassassin.py
index 150f238..9f6e45d 100644
--- a/modoboa_installer/scripts/spamassassin.py
+++ b/modoboa_installer/scripts/spamassassin.py
@@ -57,10 +57,12 @@ class Spamassassin(base.Installer):
         context = super(Spamassassin, self).get_template_context()
         if self.dbengine == "postgres":
             store_module = "Mail::SpamAssassin::BayesStore::PgSQL"
-            dsn = "DBI:Pg:dbname={};host={}".format(self.dbname, self.dbhost)
+            dsn = "DBI:Pg:dbname={};host={};port={}".format(
+                self.dbname, self.dbhost, self.dbport)
         else:
             store_module = "Mail::SpamAssassin::BayesStore::MySQL"
-            dsn = "DBI:mysql:{}:{}".format(self.dbname, self.dbhost)
+            dsn = "DBI:mysql:{}:{}:{}".format(
+                self.dbname, self.dbhost, self.dbport)
         context.update({
             "store_module": store_module, "dsn": dsn, "dcc_enabled": "#"})
         return context
diff --git a/modoboa_installer/ssl.py b/modoboa_installer/ssl.py
index 8df9b30..a0cd4d0 100644
--- a/modoboa_installer/ssl.py
+++ b/modoboa_installer/ssl.py
@@ -92,6 +92,12 @@ class LetsEncryptCertificate(CertificateBackend):
         else:
             utils.printcolor("Failed to install certbot, aborting.", utils.RED)
             sys.exit(1)
+        #Nginx plugin certbot
+        if (self.config.has_option("nginx", "enabled") and
+            self.config.getboolean("nginx", "enabled")):
+            package.backend.update()
+            package.backend.install("python3-certbot-nginx")
+            
 
     def generate_cert(self):
         """Create a certificate."""