diff --git a/README.md b/README.md
index b6c0756..22e0256 100644
--- a/README.md
+++ b/README.md
@@ -1,282 +1,282 @@
-# KopanoDocker
-Unofficial kopano docker images for all kopano services.
-Use kopano_core image for server/spooler/dagent/search/monitor/ical/gateway services.
-Use kopano_webapp for web service.
-
-Example
-=======
-
-docker-compose.yml
-```
-version: '3'
-
-services:
-
-  kserver:
-    image: zokradonh/kopano_core:${CORE_VERSION}
-    hostname: kserver
-    container_name: kopano_server
-    links:
-      - db
-    depends_on:
-      - "kssl"
-    environment:
-      - SERVICE_TO_START=server
-      - TZ=Europe/Berlin
-      - KCCONF_SERVER_COREDUMP_ENABLED=no
-      - KCCONF_SERVER_LOG_LEVEL=4
-      - KCCONF_SERVER_MYSQL_HOST=db
-      - KCCONF_SERVER_MYSQL_PORT=3306
-      - KCCONF_SERVER_MYSQL_DATABASE=kopano
-      - KCCONF_SERVER_MYSQL_USER=root
-      - KCCONF_SERVER_MYSQL_PASSWORD=YOUR_MYSQL_ROOT_PASSWORD  #change here
-      - KCCONF_SERVER_SERVER_SSL_KEY_FILE=/kopano/ssl/kserver.pem
-      - KCCONF_SERVER_SERVER_SSL_CA_FILE=/kopano/ssl/ca.pem
-      - KCCONF_SERVER_SSLKEYS_PATH=/kopano/ssl/clients
-      - KCCONF_SERVER_PROXY_HEADER=* # delete line if webapp is not behind reverse proxy
-      - KCCONF_SERVER_SYSTEM_EMAIL_ADDRESS=hostmaster@domain.tld  #change here
-      - KCCONF_SERVER_DISABLED_FEATURES=pop3
-      - KCCONF_SERVER_SEARCH_SOCKET=http://ksearch:2380/
-      - KCCONF_LDAP_LDAP_URI=ldaps://ldapserver:ldapport  #change here
-      - KCCONF_LDAP_LDAP_BIND_USER=cn=SOME_STANDARD_USER,OU=MyUsers,DC=domain,DC=tld #change here
-      - KCCONF_LDAP_LDAP_BIND_PASSWD=PASSWORD_OF_STANDARD_USER  #change here
-      - KCCONF_LDAP_LDAP_SEARCH_BASE=OU=MyUsers,dc=domain,dc=tld  #change here
-      - KCCOMMENT_LDAP_1=!include /usr/share/kopano/ldap.openldap.cfg #delete if you want openldap
-      - KCUNCOMMENT_LDAP_1=!include /usr/share/kopano/ldap.active-directory.cfg #delete if you want openldap
-    networks:
-      - kopanonet
-    volumes:
-      - data:/kopano/data
-      - sslcerts:/kopano/ssl
-
-  kdagent:
-    image: zokradonh/kopano_core:${CORE_VERSION}
-    container_name: kopano_dagent
-    links:
-      - kserver
-    volumes:
-      - sslcerts:/kopano/ssl
-    environment:
-      - SERVICE_TO_START=dagent
-      - TZ=Europe/Berlin
-      - KCCONF_DAGENT_LOG_LEVEL=6
-      - KCCONF_DAGENT_SERVER_SOCKET=https://kserver:237/
-      - KCCONF_DAGENT_SSLKEY_FILE=/kopano/ssl/kdagent.pem
-    networks:
-      - kopanonet
-
-  kgateway:
-    image: zokradonh/kopano_core:${CORE_VERSION}
-    container_name: kopano_gateway
-    links:
-      - kserver
-    volumes:
-      - ./gatewaycerts/:/kopano/certs/
-    environment:
-      - SERVICE_TO_START=gateway
-      - TZ=Europe/Berlin
-      - KCCONF_GATEWAY_SERVER_SOCKET=http://kserver:236/
-      - KCCONF_GATEWAY_SSL_PRIVATE_KEY_FILE=/kopano/certs/yourcert.key # change here
-      - KCCONF_GATEWAY_SSL_CERTIFICATE_FILE=/kopano/certs/yourcert.pem # change here
-    networks:
-      - kopanonet
-
-  kical:
-    image: zokradonh/kopano_core:${CORE_VERSION}
-    container_name: kopano_ical
-    links:
-      - kserver
-    environment:
-      - SERVICE_TO_START=ical
-      - TZ=Europe/Berlin
-      - KCCONF_ICAL_SERVER_SOCKET=http://kserver:236/
-    networks:
-      - kopanonet
-
-  kmonitor:
-    image: zokradonh/kopano_core:${CORE_VERSION}
-    container_name: kopano_monitor
-    links:
-      - kserver
-    volumes:
-      - sslcerts:/kopano/ssl
-    environment:
-      - SERVICE_TO_START=monitor
-      - TZ=Europe/Berlin
-      - KCCONF_MONITOR_SERVER_SOCKET=https://kserver:237/
-      - KCCONF_MONITOR_SSLKEY_FILE=/kopano/ssl/kmonitor.pem
-    networks:
-      - kopanonet
-
-  ksearch:
-    image: zokradonh/kopano_core:${CORE_VERSION}
-    container_name: kopano_search
-    links:
-      - kserver
-    volumes:
-      - sslcerts:/kopano/ssl
-    environment:
-      - SERVICE_TO_START=search
-      - TZ=Europe/Berlin
-      - KCCONF_SEARCH_SERVER_BIND_NAME=http://ksearch:2380
-      - KCCONF_SEARCH_SERVER_SOCKET=https://kserver:237/
-      - KCCONF_SEARCH_SSLKEY_FILE=/kopano/ssl/ksearch.pem
-    networks:
-      - kopanonet
-
-  kspooler:
-    image: zokradonh/kopano_core:${CORE_VERSION}
-    container_name: kopano_spooler
-    links:
-      - kserver
-    volumes:
-      - sslcerts:/kopano/ssl
-    environment:
-      - SERVICE_TO_START=spooler
-      - TZ=Europe/Berlin
-      - KCCONF_SPOOLER_SERVER_SOCKET=https://kserver:237/
-      - KCCONF_SPOOLER_LOG_LEVEL=4
-      - KCCONF_SPOOLER_SMTP_SERVER=kmta
-      - KCCONF_SPOOLER_SSLKEY_FILE=/kopano/ssl/kspooler.pem
-    networks:
-      - kopanonet
-
-  kwebapp:
-    image: zokradonh/kopano_webapp:${WEBAPP_VERSION}
-    hostname: kwebapp
-    container_name: kopano_webapp
-    links:
-      - kserver
-    #ports:
-    #  - "8236:80"
-    #  - "8237:443"
-    volumes:
-      - syncstates:/var/lib/z-push/
-      - sslcerts:/kopano/ssl
-    environment:
-      - TZ=Europe/Berlin
-      - KCCONF_SERVERHOSTNAME=kserver
-      - KCCONF_SERVERPORT=237
-    networks:
-      - web
-      - kopanonet
-
-  kssl:
-    image: zokradonh/kopano_ssl
-    container_name: kopano_ssl
-    volumes:
-      - sslcerts:/kopano/ssl
-
-  kmta:
-    image: tvial/docker-mailserver:latest
-    hostname: myhost #change here
-    domainname: domain.tld #change here
-    #dns: 127.0.0.1
-    container_name: kopano_mta
-    #links:
-    #  - adtunnel
-    ports:
-      - "25:25"
-    #  - "143:143"
-    #  - "587:587"
-    #  - "993:993"
-    volumes:
-      - tmpmaildata:/var/mail
-      - tmpmailstate:/var/mail-state
-      - ./mtaconfig/:/tmp/docker-mailserver/ # create this dir
-    environment:
-      - TZ=Europe/Berlin
-      - ENABLE_SPAMASSASSIN=1
-      - ENABLE_CLAMAV=1
-      - ENABLE_FAIL2BAN=1
-      - ENABLE_POSTGREY=1
-      - TLS_LEVEL=intermediate
-      - POSTGREY_DELAY=10
-      - ONE_DIR=1
-      - DMS_DEBUG=0
-      - ENABLE_LDAP=1
-      - LDAP_SERVER_HOST=ldaps://ldapserver:ldapport #change here
-      - LDAP_SEARCH_BASE=OU=MyUsers,DC=domain,DC=tld #change here
-      - LDAP_BIND_DN=cn=SOME_STANDARD_USER,OU=MyUsers,DC=domain,DC=tld #change here
-      - LDAP_BIND_PW=PASSWORD_OF_SOME_STANDARD_USER #change here
-      - LDAP_QUERY_FILTER_USER=(&(objectClass=user)(|(mail=%s)(otherMailbox=%s)))
-      - LDAP_QUERY_FILTER_GROUP=(&(objectclass=group)(mail=%s))
-      - LDAP_QUERY_FILTER_ALIAS=(&(objectClass=user)(otherMailbox=%s))
-      - LDAP_QUERY_FILTER_DOMAIN=(&(|(mail=*@%s)(otherMailbox=*@%s)(mailGroupMember=*@%s))(kopanoAccount=1)(|(objectClass=user)(objectclass=group)))
-      - ENABLE_SASLAUTHD=1
-      - SASLAUTHD_LDAP_SERVER=ldaps://ldapserver:ldapport #change here
-      - SASLAUTHD_LDAP_BIND_DN=cn=SOME_STANDARD_USER,OU=MyUsers,DC=domain,DC=tld #change here
-      - SASLAUTHD_LDAP_PASSWORD=PASSWORD_OF_SOME_STANDARD_USER  #change here
-      - SASLAUTHD_LDAP_SEARCH_BASE=OU=MyUsers,DC=domain,DC=tld  #change here
-      - SASLAUTHD_LDAP_FILTER=(&(sAMAccountName=%U)(objectClass=person))
-      - SASLAUTHD_MECHANISMS=ldap
-      - POSTMASTER_ADDRESS=postmaster@domain.tld #change here
-      - SMTP_ONLY=1
-      - PERMIT_DOCKER=network
-      - ENABLE_POSTFIX_VIRTUAL_TRANSPORT=1
-      - POSTFIX_DAGENT=lmtp:kdagent:2003
-      - REPORT_RECIPIENT=1
-    networks:
-      - kopanonet
-    cap_add:
-      - NET_ADMIN
-      - SYS_PTRACE
-
-  db:
-    image: mariadb
-    restart: always
-    container_name: kopano_db
-    volumes:
-      - db:/var/lib/mysql
-    environment:
-      - MYSQL_ROOT_PASSWORD=YOUR_MYSQL_ROOT_PASSWORD  #change here
-      - MYSQL_PASSWORD=YOUR_PASSWORD #change here
-      - MYSQL_DATABASE=kopano
-      - MYSQL_USER=kopano
-    networks:
-      - kopanonet
-
-volumes:
-  db:
-  data:
-  syncstates:
-  sslcerts:
-  tmpmaildata:
-  tmpmailstate:
-
-networks:
-  web: # this requires an external docker container that is a http reverse proxy (e.g. haproxy)
-    external:
-      name: haproxy_webrproxynet
-  kopanonet:
-    driver: bridge
-```
-
-Requires haproxy network for http reverse proxy.
-Change all lines which are commented especially those with #change here
-
-This is just a quick example docker-compose.yml made in some minutes to provide a better start.
-
-Requires `.env` file next to docker-compose.yml with content like this
-```
-CORE_VERSION=8.6.80.1055-0plus156.1
-WEBAPP_VERSION=3.4.17.1565plus895.1
-```
-
-Requires `ldap-groups.cf` in ./mtaconfig directory next to docker-compose.yml
-```
-bind                     = yes
-bind_dn                  = cn=admin,dc=domain,dc=com
-bind_pw                  = admin
-query_filter             = (&(mailGroupMember=%s)(mailEnabled=TRUE))
-result_attribute         = mail
-search_base              = ou=people,dc=domain,dc=com
-server_host              = mail.domain.com
-start_tls                = no
-version                  = 3
-leaf_result_attribute = mail
-special_result_attribute = member
-```
-Now group members of Active Directory groups can be found by postfix.
-
-Furthermore you can use this directory for opendkim - see kmta's image for details.
+# Kopano Docker Image
+Unofficial kopano docker images for all kopano services.
+Use kopano_core image for server/spooler/dagent/search/monitor/ical/gateway services.
+Use kopano_webapp for web service.
+
+Example
+=======
+
+docker-compose.yml
+```
+version: '3'
+
+services:
+
+  kserver:
+    image: zokradonh/kopano_core:${CORE_VERSION}
+    hostname: kserver
+    container_name: kopano_server
+    links:
+      - db
+    depends_on:
+      - "kssl"
+    environment:
+      - SERVICE_TO_START=server
+      - TZ=Europe/Berlin
+      - KCCONF_SERVER_COREDUMP_ENABLED=no
+      - KCCONF_SERVER_LOG_LEVEL=4
+      - KCCONF_SERVER_MYSQL_HOST=db
+      - KCCONF_SERVER_MYSQL_PORT=3306
+      - KCCONF_SERVER_MYSQL_DATABASE=kopano
+      - KCCONF_SERVER_MYSQL_USER=root
+      - KCCONF_SERVER_MYSQL_PASSWORD=YOUR_MYSQL_ROOT_PASSWORD  #change here
+      - KCCONF_SERVER_SERVER_SSL_KEY_FILE=/kopano/ssl/kserver.pem
+      - KCCONF_SERVER_SERVER_SSL_CA_FILE=/kopano/ssl/ca.pem
+      - KCCONF_SERVER_SSLKEYS_PATH=/kopano/ssl/clients
+      - KCCONF_SERVER_PROXY_HEADER=* # delete line if webapp is not behind reverse proxy
+      - KCCONF_SERVER_SYSTEM_EMAIL_ADDRESS=hostmaster@domain.tld  #change here
+      - KCCONF_SERVER_DISABLED_FEATURES=pop3
+      - KCCONF_SERVER_SEARCH_SOCKET=http://ksearch:2380/
+      - KCCONF_LDAP_LDAP_URI=ldaps://ldapserver:ldapport  #change here
+      - KCCONF_LDAP_LDAP_BIND_USER=cn=SOME_STANDARD_USER,OU=MyUsers,DC=domain,DC=tld #change here
+      - KCCONF_LDAP_LDAP_BIND_PASSWD=PASSWORD_OF_STANDARD_USER  #change here
+      - KCCONF_LDAP_LDAP_SEARCH_BASE=OU=MyUsers,dc=domain,dc=tld  #change here
+      - KCCOMMENT_LDAP_1=!include /usr/share/kopano/ldap.openldap.cfg #delete if you want openldap
+      - KCUNCOMMENT_LDAP_1=!include /usr/share/kopano/ldap.active-directory.cfg #delete if you want openldap
+    networks:
+      - kopanonet
+    volumes:
+      - data:/kopano/data
+      - sslcerts:/kopano/ssl
+
+  kdagent:
+    image: zokradonh/kopano_core:${CORE_VERSION}
+    container_name: kopano_dagent
+    links:
+      - kserver
+    volumes:
+      - sslcerts:/kopano/ssl
+    environment:
+      - SERVICE_TO_START=dagent
+      - TZ=Europe/Berlin
+      - KCCONF_DAGENT_LOG_LEVEL=6
+      - KCCONF_DAGENT_SERVER_SOCKET=https://kserver:237/
+      - KCCONF_DAGENT_SSLKEY_FILE=/kopano/ssl/kdagent.pem
+    networks:
+      - kopanonet
+
+  kgateway:
+    image: zokradonh/kopano_core:${CORE_VERSION}
+    container_name: kopano_gateway
+    links:
+      - kserver
+    volumes:
+      - ./gatewaycerts/:/kopano/certs/
+    environment:
+      - SERVICE_TO_START=gateway
+      - TZ=Europe/Berlin
+      - KCCONF_GATEWAY_SERVER_SOCKET=http://kserver:236/
+      - KCCONF_GATEWAY_SSL_PRIVATE_KEY_FILE=/kopano/certs/yourcert.key # change here
+      - KCCONF_GATEWAY_SSL_CERTIFICATE_FILE=/kopano/certs/yourcert.pem # change here
+    networks:
+      - kopanonet
+
+  kical:
+    image: zokradonh/kopano_core:${CORE_VERSION}
+    container_name: kopano_ical
+    links:
+      - kserver
+    environment:
+      - SERVICE_TO_START=ical
+      - TZ=Europe/Berlin
+      - KCCONF_ICAL_SERVER_SOCKET=http://kserver:236/
+    networks:
+      - kopanonet
+
+  kmonitor:
+    image: zokradonh/kopano_core:${CORE_VERSION}
+    container_name: kopano_monitor
+    links:
+      - kserver
+    volumes:
+      - sslcerts:/kopano/ssl
+    environment:
+      - SERVICE_TO_START=monitor
+      - TZ=Europe/Berlin
+      - KCCONF_MONITOR_SERVER_SOCKET=https://kserver:237/
+      - KCCONF_MONITOR_SSLKEY_FILE=/kopano/ssl/kmonitor.pem
+    networks:
+      - kopanonet
+
+  ksearch:
+    image: zokradonh/kopano_core:${CORE_VERSION}
+    container_name: kopano_search
+    links:
+      - kserver
+    volumes:
+      - sslcerts:/kopano/ssl
+    environment:
+      - SERVICE_TO_START=search
+      - TZ=Europe/Berlin
+      - KCCONF_SEARCH_SERVER_BIND_NAME=http://ksearch:2380
+      - KCCONF_SEARCH_SERVER_SOCKET=https://kserver:237/
+      - KCCONF_SEARCH_SSLKEY_FILE=/kopano/ssl/ksearch.pem
+    networks:
+      - kopanonet
+
+  kspooler:
+    image: zokradonh/kopano_core:${CORE_VERSION}
+    container_name: kopano_spooler
+    links:
+      - kserver
+    volumes:
+      - sslcerts:/kopano/ssl
+    environment:
+      - SERVICE_TO_START=spooler
+      - TZ=Europe/Berlin
+      - KCCONF_SPOOLER_SERVER_SOCKET=https://kserver:237/
+      - KCCONF_SPOOLER_LOG_LEVEL=4
+      - KCCONF_SPOOLER_SMTP_SERVER=kmta
+      - KCCONF_SPOOLER_SSLKEY_FILE=/kopano/ssl/kspooler.pem
+    networks:
+      - kopanonet
+
+  kwebapp:
+    image: zokradonh/kopano_webapp:${WEBAPP_VERSION}
+    hostname: kwebapp
+    container_name: kopano_webapp
+    links:
+      - kserver
+    #ports:
+    #  - "8236:80"
+    #  - "8237:443"
+    volumes:
+      - syncstates:/var/lib/z-push/
+      - sslcerts:/kopano/ssl
+    environment:
+      - TZ=Europe/Berlin
+      - KCCONF_SERVERHOSTNAME=kserver
+      - KCCONF_SERVERPORT=237
+    networks:
+      - web
+      - kopanonet
+
+  kssl:
+    image: zokradonh/kopano_ssl
+    container_name: kopano_ssl
+    volumes:
+      - sslcerts:/kopano/ssl
+
+  kmta:
+    image: tvial/docker-mailserver:latest
+    hostname: myhost #change here
+    domainname: domain.tld #change here
+    #dns: 127.0.0.1
+    container_name: kopano_mta
+    #links:
+    #  - adtunnel
+    ports:
+      - "25:25"
+    #  - "143:143"
+    #  - "587:587"
+    #  - "993:993"
+    volumes:
+      - tmpmaildata:/var/mail
+      - tmpmailstate:/var/mail-state
+      - ./mtaconfig/:/tmp/docker-mailserver/ # create this dir
+    environment:
+      - TZ=Europe/Berlin
+      - ENABLE_SPAMASSASSIN=1
+      - ENABLE_CLAMAV=1
+      - ENABLE_FAIL2BAN=1
+      - ENABLE_POSTGREY=1
+      - TLS_LEVEL=intermediate
+      - POSTGREY_DELAY=10
+      - ONE_DIR=1
+      - DMS_DEBUG=0
+      - ENABLE_LDAP=1
+      - LDAP_SERVER_HOST=ldaps://ldapserver:ldapport #change here
+      - LDAP_SEARCH_BASE=OU=MyUsers,DC=domain,DC=tld #change here
+      - LDAP_BIND_DN=cn=SOME_STANDARD_USER,OU=MyUsers,DC=domain,DC=tld #change here
+      - LDAP_BIND_PW=PASSWORD_OF_SOME_STANDARD_USER #change here
+      - LDAP_QUERY_FILTER_USER=(&(objectClass=user)(|(mail=%s)(otherMailbox=%s)))
+      - LDAP_QUERY_FILTER_GROUP=(&(objectclass=group)(mail=%s))
+      - LDAP_QUERY_FILTER_ALIAS=(&(objectClass=user)(otherMailbox=%s))
+      - LDAP_QUERY_FILTER_DOMAIN=(&(|(mail=*@%s)(otherMailbox=*@%s)(mailGroupMember=*@%s))(kopanoAccount=1)(|(objectClass=user)(objectclass=group)))
+      - ENABLE_SASLAUTHD=1
+      - SASLAUTHD_LDAP_SERVER=ldaps://ldapserver:ldapport #change here
+      - SASLAUTHD_LDAP_BIND_DN=cn=SOME_STANDARD_USER,OU=MyUsers,DC=domain,DC=tld #change here
+      - SASLAUTHD_LDAP_PASSWORD=PASSWORD_OF_SOME_STANDARD_USER  #change here
+      - SASLAUTHD_LDAP_SEARCH_BASE=OU=MyUsers,DC=domain,DC=tld  #change here
+      - SASLAUTHD_LDAP_FILTER=(&(sAMAccountName=%U)(objectClass=person))
+      - SASLAUTHD_MECHANISMS=ldap
+      - POSTMASTER_ADDRESS=postmaster@domain.tld #change here
+      - SMTP_ONLY=1
+      - PERMIT_DOCKER=network
+      - ENABLE_POSTFIX_VIRTUAL_TRANSPORT=1
+      - POSTFIX_DAGENT=lmtp:kdagent:2003
+      - REPORT_RECIPIENT=1
+    networks:
+      - kopanonet
+    cap_add:
+      - NET_ADMIN
+      - SYS_PTRACE
+
+  db:
+    image: mariadb
+    restart: always
+    container_name: kopano_db
+    volumes:
+      - db:/var/lib/mysql
+    environment:
+      - MYSQL_ROOT_PASSWORD=YOUR_MYSQL_ROOT_PASSWORD  #change here
+      - MYSQL_PASSWORD=YOUR_PASSWORD #change here
+      - MYSQL_DATABASE=kopano
+      - MYSQL_USER=kopano
+    networks:
+      - kopanonet
+
+volumes:
+  db:
+  data:
+  syncstates:
+  sslcerts:
+  tmpmaildata:
+  tmpmailstate:
+
+networks:
+  web: # this requires an external docker container that is a http reverse proxy (e.g. haproxy)
+    external:
+      name: haproxy_webrproxynet
+  kopanonet:
+    driver: bridge
+```
+
+Requires haproxy network for http reverse proxy.
+Change all lines which are commented especially those with #change here
+
+This is just a quick example docker-compose.yml made in some minutes to provide a better start.
+
+Requires `.env` file next to docker-compose.yml with content like this
+```
+CORE_VERSION=8.6.80.1055-0plus156.1
+WEBAPP_VERSION=3.4.17.1565plus895.1
+```
+
+Requires `ldap-groups.cf` in ./mtaconfig directory next to docker-compose.yml
+```
+bind                     = yes
+bind_dn                  = cn=admin,dc=domain,dc=com
+bind_pw                  = admin
+query_filter             = (&(mailGroupMember=%s)(mailEnabled=TRUE))
+result_attribute         = mail
+search_base              = ou=people,dc=domain,dc=com
+server_host              = mail.domain.com
+start_tls                = no
+version                  = 3
+leaf_result_attribute = mail
+special_result_attribute = member
+```
+Now group members of Active Directory groups can be found by postfix.
+
+Furthermore you can use this directory for opendkim - see kmta's image for details.
diff --git a/core/Dockerfile b/core/Dockerfile
index f6e9e3b..f935a08 100644
--- a/core/Dockerfile
+++ b/core/Dockerfile
@@ -17,7 +17,7 @@ RUN apt-get update && \
         moreutils \
         locales \
         apt-transport-https \
-        python3 && \
+        python3-minimal && \
     rm -rf /var/cache/apt /var/lib/apt/lists
 
 RUN curl -s -S -L -o /usr/local/bin/confix https://raw.githubusercontent.com/budhash/confix/master/confix && \
@@ -38,6 +38,7 @@ ARG KOPANO_REPOSITORY_BRANCH=master
 ARG KOPANO_CORE_REPOSITORY_URL="http://buildproxy/supported/core:/${KOPANO_REPOSITORY_BRANCH}/Debian_9.0"
 ARG KOPANO_REPOSITORY_FLAGS="trusted=yes"
 ARG NO_RELEASE_KEY_DOWNLOAD=0
+ARG ADDITIONAL_KOPANO_PACKAGES
 
 # install kopano components
 RUN set -x && \
@@ -47,6 +48,7 @@ RUN set -x && \
     apt-get update && \
     apt-get install --no-install-recommends -y \
         kopano-server-packages="${KOPANO_CORE_VERSION}" \
+        ${ADDITIONAL_KOPANO_PACKAGES} \
         php7.0-cli && \
     rm -rf /var/cache/apt /var/lib/apt/lists && \
     cp /usr/share/doc/kopano/example-config/*.cfg /etc/kopano/ && \