diff --git a/core/dovecot/start.py b/core/dovecot/start.py
index 2feaf912..83f91fab 100755
--- a/core/dovecot/start.py
+++ b/core/dovecot/start.py
@@ -8,10 +8,10 @@ import glob
 convert = lambda src, dst: open(dst, "w").write(jinja2.Template(open(src).read()).render(**os.environ))
 
 # Actual startup script
-os.environ["FRONT_ADDRESS"] = socket.gethostbyname("front")
-os.environ["REDIS_ADDRESS"] = socket.gethostbyname("redis")
+os.environ["FRONT_ADDRESS"] = socket.gethostbyname(os.environ.get("FRONT_ADDRESS", "front"))
+os.environ["REDIS_ADDRESS"] = socket.gethostbyname(os.environ.get("REDIS_ADDRESS", "redis"))
 if os.environ["WEBMAIL"] != "none":
-	os.environ["WEBMAIL_ADDRESS"] = socket.gethostbyname("webmail")
+	os.environ["WEBMAIL_ADDRESS"] = socket.gethostbyname(os.environ.get("WEBMAIL_ADDRESS", "webmail"))
 
 for dovecot_file in glob.glob("/conf/*"):
     convert(dovecot_file, os.path.join("/etc/dovecot", os.path.basename(dovecot_file)))
diff --git a/core/postfix/conf/main.cf b/core/postfix/conf/main.cf
index ea210129..2f2c6990 100644
--- a/core/postfix/conf/main.cf
+++ b/core/postfix/conf/main.cf
@@ -63,7 +63,7 @@ virtual_mailbox_maps = $virtual_alias_maps
 # Mails are transported if required, then forwarded to Dovecot for delivery
 relay_domains = ${sql}sqlite-transport.cf
 transport_maps = ${sql}sqlite-transport.cf
-virtual_transport = lmtp:inet:imap:2525
+virtual_transport = lmtp:inet:{{ HOST_LMTP }}
 
 # In order to prevent Postfix from running DNS query, enforce the use of the
 # native DNS stack, that will check /etc/hosts properly.
@@ -97,7 +97,7 @@ unverified_recipient_reject_reason = Address lookup failure
 # Milter
 ###############
 
-smtpd_milters = inet:antispam:11332
+smtpd_milters = inet:{{ HOST_ANTISPAM }}
 milter_protocol = 6
 milter_mail_macros = i {mail_addr} {client_addr} {client_name} {auth_authen}
 milter_default_action = tempfail
diff --git a/core/postfix/start.py b/core/postfix/start.py
index 994c4431..4dbf2206 100755
--- a/core/postfix/start.py
+++ b/core/postfix/start.py
@@ -9,7 +9,9 @@ import shutil
 convert = lambda src, dst: open(dst, "w").write(jinja2.Template(open(src).read()).render(**os.environ))
 
 # Actual startup script
-os.environ["FRONT_ADDRESS"] = socket.gethostbyname("front")
+os.environ["FRONT_ADDRESS"] = socket.gethostbyname(os.environ.get("FRONT_ADDRESS", "front"))
+os.environ["HOST_ANTISPAM"] = os.environ.get("HOST_ANTISPAM", "antispam:11332")
+os.environ["HOST_LMTP"] = os.environ.get("HOST_LMTP", "imap:2525")
 
 for postfix_file in glob.glob("/conf/*.cf"):
     convert(postfix_file, os.path.join("/etc/postfix", os.path.basename(postfix_file)))
diff --git a/docs/configuration.rst b/docs/configuration.rst
index 0fb5daf1..62b6f34e 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -79,6 +79,8 @@ to find the location of the other containers it depends on. They can contain an
 optional port number. Those variables are:
 
 - ``HOST_IMAP``: the container that is running the IMAP server (default: ``imap``, port 143)
+- ``HOST_LMTP``: the container that is running the LMTP server (default: ``imap:2525``)
+- ``HOST_HOSTIMAP``: the container that is running the IMAP server for the webmail (default: ``imap``, port 10143)
 - ``HOST_POP3``: the container that is running the POP3 server (default: ``imap``, port 110)
 - ``HOST_SMTP``: the container that is running the SMTP server (default: ``smtp``, port 25)
 - ``HOST_AUTHSMTP``: the container that is running the authenticated SMTP server for the webnmail (default: ``smtp``, port 10025)
@@ -86,4 +88,12 @@ optional port number. Those variables are:
 - ``HOST_ANTISPAM``: the container that is running the antispam service (default: ``antispam:11334``)
 - ``HOST_WEBMAIL``: the container that is running the webmail (default: ``webmail``)
 - ``HOST_WEBDAV``: the container that is running the webdav server (default: ``webdav:5232``)
+- ``HOST_REDIS``: the container that is running the redis daemon (default: ``redis``)
 
+Additional variables are used to locate other containers without dialing a
+specific port number. It is used to either whitelist connection from these
+addresses or connect to containers on the docker network:
+
+- ``FRONT_ADDRESS``: the nginx container address (default: ``front``)
+- ``WEBMAIL_ADDRESS``: the webmail container address (default: ``webmail``)
+- ``IMAP_ADDRESS``: the webmail container address (default: ``webmail``)
diff --git a/services/fetchmail/fetchmail.py b/services/fetchmail/fetchmail.py
index 3ef218de..6aeea3e7 100755
--- a/services/fetchmail/fetchmail.py
+++ b/services/fetchmail/fetchmail.py
@@ -6,6 +6,7 @@ import os
 import tempfile
 import shlex
 import subprocess
+import re
 
 
 FETCHMAIL = """
@@ -18,11 +19,14 @@ RC_LINE = """
 poll "{host}" proto {protocol}  port {port}
     user "{username}" password "{password}"
     is "{user_email}"
-    smtphost "smtp"
+    smtphost "{smtphost}"
     {options}
     sslproto 'AUTO'
 """
 
+def extract_host_port(host_and_port, default_port):
+    host, _, port = re.match('^(.*)(:([0-9]*))?$', host_and_port).groups()
+    return host, int(port) if port else default_port
 
 def escape_rc_string(arg):
     return arg.replace("\\", "\\\\").replace('"', '\\"')
@@ -42,6 +46,11 @@ def run(connection, cursor, debug):
         SELECT user_email, protocol, host, port, tls, username, password, keep
         FROM fetch
     """)
+    smtphost, smtpport = extract_host_port(os.environ.get("HOST_SMTP", "smtp"), None)
+    if smtpport is None:
+        smtphostport = smtphost
+    else:
+        smtphostport = "%s/%d" % (smtphost, smtpport)
     for line in cursor.fetchall():
         fetchmailrc = ""
         user_email, protocol, host, port, tls, username, password, keep = line
@@ -53,6 +62,7 @@ def run(connection, cursor, debug):
             protocol=protocol,
             host=escape_rc_string(host),
             port=port,
+            smtphost=smtphostport,
             username=escape_rc_string(username),
             password=escape_rc_string(password),
             options=options
diff --git a/services/rspamd/conf/redis.conf b/services/rspamd/conf/redis.conf
index 57f2f4ec..fee07024 100644
--- a/services/rspamd/conf/redis.conf
+++ b/services/rspamd/conf/redis.conf
@@ -1 +1 @@
-servers = "redis";
+servers = "{{ HOST_REDIS }}";
diff --git a/services/rspamd/start.py b/services/rspamd/start.py
index 9d7d0cf0..87309cee 100755
--- a/services/rspamd/start.py
+++ b/services/rspamd/start.py
@@ -8,7 +8,8 @@ import glob
 convert = lambda src, dst: open(dst, "w").write(jinja2.Template(open(src).read()).render(**os.environ))
 
 # Actual startup script
-os.environ["FRONT_ADDRESS"] = socket.gethostbyname("front")
+os.environ["FRONT_ADDRESS"] = socket.gethostbyname(os.environ.get("FRONT_ADDRESS", "front"))
+if "HOST_REDIS" not in os.environ: os.environ["HOST_REDIS"] = "redis"
 
 for rspamd_file in glob.glob("/conf/*"):
     convert(rspamd_file, os.path.join("/etc/rspamd/local.d", os.path.basename(rspamd_file)))
diff --git a/webmails/rainloop/default.ini b/webmails/rainloop/default.ini
index fd7cfba7..b77281f4 100644
--- a/webmails/rainloop/default.ini
+++ b/webmails/rainloop/default.ini
@@ -1,13 +1,13 @@
-imap_host = "front"
+imap_host = "%FRONT_ADDRESS%"
 imap_port = 10143
 imap_secure = "None"
 imap_short_login = Off
 sieve_use = On
 sieve_allow_raw = Off
-sieve_host = "imap"
+sieve_host = "%IMAP_ADDRESS%"
 sieve_port = 4190
 sieve_secure = "None"
-smtp_host = "front"
+smtp_host = "%FRONT_ADDRESS%"
 smtp_port = 10025
 smtp_secure = "None"
 smtp_short_login = Off
diff --git a/webmails/rainloop/start.sh b/webmails/rainloop/start.sh
index bbe9e211..f43983d0 100755
--- a/webmails/rainloop/start.sh
+++ b/webmails/rainloop/start.sh
@@ -1,11 +1,17 @@
 #!/bin/sh
 
+template(){
+  sed \
+    -e "s/%FRONT_ADDRESS%/$FRONT_ADDRESS/g" \
+    -e "s/%IMAP_ADDRESS%/$IMAP_ADDRESS/g"
+}
+
 # There is no cleaner way to setup the default SMTP/IMAP server or to
 # override the configuration
 rm -f /data/_data_/_default_/domains/*
 mkdir -p /data/_data_/_default_/domains/ /data/_data_/_default_/configs/
-cp /default.ini /data/_data_/_default_/domains/
-cp /config.ini /data/_data_/_default_/configs/
+template </default.ini >/data/_data_/_default_/domains/default.ini
+template </config.ini  >/data/_data_/_default_/configs/config.ini
 
 # Fix some permissions
 chown -R www-data:www-data /data
diff --git a/webmails/roundcube/config.inc.php b/webmails/roundcube/config.inc.php
index 6707e437..379b3025 100644
--- a/webmails/roundcube/config.inc.php
+++ b/webmails/roundcube/config.inc.php
@@ -19,15 +19,15 @@ $config['plugins'] = array(
 );
 
 // Mail servers
-$config['default_host'] = 'front';
+$config['default_host'] = getenv('FRONT_ADDRESS') || 'front';
 $config['default_port'] = 10143;
-$config['smtp_server'] = 'front';
+$config['smtp_server'] = getenv('FRONT_ADDRESS') || 'front';
 $config['smtp_port'] = 10025;
 $config['smtp_user'] = '%u';
 $config['smtp_pass'] = '%p';
 
 // Sieve script management
-$config['managesieve_host'] = 'imap';
+$config['managesieve_host'] = getenv('IMAP_ADDRESS') || 'imap';
 $config['managesieve_usetls'] = false;
 
 // We access the IMAP and SMTP servers locally with internal names, SSL