# The `mlan/kopano` repository

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This (non official) repository provides dockerized web mail service as well as Exchange ActiveSync (EAS), IMAP, POP3 and ICAL service (and their secure variants  IMAPS, POP3S and ICALS). It is based on [Kopano](https://kopano.com) core components, as well as the Kopano WebApp and [Z-Push](http://z-push.org/). The image uses [nightly built packages](https://download.kopano.io/community/) which are provided by the Kopano community.

Hopefully this repository can be retired once the Kopano community make official images available. To learn more about this activity see [zokradonh/kopano-docker](https://github.com/zokradonh/kopano-docker).

## Features

- Groupware server [Kopano WebApp](https://kopano.io/)
- [Exchange ActiveSync (EAS)](https://en.wikipedia.org/wiki/Exchange_ActiveSync) server [Z-Push](http://z-push.org/)
- IMAP, POP3 and ICAL service Kopano
- Secure protocols IMAPS, POP3S and ICALS.
- Hooks for integrating [Let’s Encrypt](https://letsencrypt.org/) LTS certificates using the reverse proxy [Traefik](https://docs.traefik.io/)
- Multi-staged build providing the images `full` and `core`
- Configuration using environment variables
- Log directed to docker daemon with configurable level
- Built in utility script [run](src/docker/bin/run) helping configuring Kopano components, WebApp and Z-Push
- Health check
- Hook for theming
- Demo based on `docker-compose.yml` and `Makefile` files

## Tags

The `mlan/kopano` repository contains a multi staged built. You select which build using the appropriate tag.

The version part of the tag is not based on the version of this repository. It is instead, based on the combined revision numbers of the nightly Kopano core and Kopano WebApp package suits that was available when building the images. For example, `8.7.80-3.5.2` indicates that the image was built using the 8.7.80 version of Kopano core and 3.5.2 version of Kopano WebApp.

The build part of the tag is one of `full` and `core`. The image with tag `full` contain Kopano core components, as well as, the Kopano WebApp and Z-Push. The image with tag `core` contains the Kopano core components proving the server and IMAP, POP3 and ICAL access, but no web access.

The tags `latest`, `full`, or `core` all reference the most recent builds.

To exemplify the usage of the tags, lets assume that the latest version tag is `8.7.80-3.5.2`. In this case `latest`, `8.7.80-3.5.2`, `full`, and `full-8.7.80-3.5.2` all identify the same image.

# Usage

In most use cases the `mlan/kopano` container also needs a SQL database (e.g., [MySQL](https://hub.docker.com/_/mysql) or [MariaDB](https://hub.docker.com/_/mariadb)), Mail Transfer Agent (e.g., [Postfix](http://www.postfix.org/)) and authentication (e.g., [OpenLDAP](https://www.openldap.org/)). Docker images of such services are available.

Often you want to configure Kopano and its components. There are
different methods available to achieve this. You can use the environment
variables described below set in the shell before creating the container.
These environment variables can also be explicitly given on
the command line when creating the container. They can also be given in
an `docker-compose.yml` file (and the `.env` file), see below. Moreover docker
volumes or host directories with desired configuration files can be
mounted in the container. And finally you can exec into a running container and modify configuration files directly.

The docker compose example below is used to demonstrate how to configure these services.

## Docker compose example

An example of how to configure an web mail server using docker compose is given below. It defines 4 services, `app`, `mta`, `db` and `auth`, which are the web mail server, the mail transfer agent, the SQL database and LDAP authentication respectively.

```yaml
version: '3'

services:
   app:
    image: mlan/kopano
    networks:
      - backend
    ports:
      - "127.0.0.1:8008:80"    # WebApp & EAS (alt. HTTP)
      - "127.0.0.1:143:143"    # IMAP (not needed if all devices can use EAS)
      - "127.0.0.1:110:110"    # POP3 (not needed if all devices can use EAS)
      - "127.0.0.1:8080:8080"  # ICAL (not needed if all devices can use EAS)
      - "127.0.0.1:993:993"    # IMAPS (not needed if all devices can use EAS)
      - "127.0.0.1:995:995"    # POP3S (not needed if all devices can use EAS)
      - "127.0.0.1:8443:8443"  # ICALS (not needed if all devices can use EAS)
    depends_on:
      - auth
      - db
      - mta
    environment: # Virgin config, ignored on restarts unless FORCE_CONFIG given.
      - USER_PLUGIN=ldap
      - LDAP_URI=ldap://auth:389/
      - MYSQL_HOST=db
      - SMTP_SERVER=mta
      - LDAP_SEARCH_BASE=${LDAP_BASE-dc=example,dc=com}
      - LDAP_USER_TYPE_ATTRIBUTE_VALUE=${LDAP_USEROBJ-posixAccount}
      - LDAP_GROUP_TYPE_ATTRIBUTE_VALUE=${LDAP_GROUPOBJ-posixGroup}
      - MYSQL_DATABASE=${MYSQL_DATABASE-kopano}
      - MYSQL_USER=${MYSQL_USER-kopano}
      - MYSQL_PASSWORD=${MYSQL_PASSWORD-secret}
      - IMAP_LISTEN=*:143                       # also listen to eth0
      - POP3_LISTEN=*:110                       # also listen to eth0
      - ICAL_LISTEN=*:8080                      # also listen to eth0
      - IMAPS_LISTEN=*:993                      # enable TLS
      - POP3S_LISTEN=*:995                      # enable TLS
      - ICALS_LISTEN=*:8443                     # enable TLS
      - DISABLED_FEATURES=${DISABLED_FEATURES-} # also enable IMAP and POP3
      - SYSLOG_LEVEL=${SYSLOG_LEVEL-3}
    volumes:
      - app-conf:/etc/kopano
      - app-atch:/var/lib/kopano/attachments
      - app-sync:/var/lib/z-push
      - app-spam:/var/lib/kopano/spamd          # kopano-spamd integration
      - /etc/localtime:/etc/localtime:ro        # Use host timezone
    cap_add: # helps debugging by allowing strace
      - sys_ptrace

  mta:
    image: mlan/postfix-amavis
    hostname: ${MAIL_SRV-mx}.${MAIL_DOMAIN-example.com}
    networks:
      - backend
    ports:
      - "127.0.0.1:25:25"      # SMTP
    depends_on:
      - auth
    environment: # Virgin config, ignored on restarts unless FORCE_CONFIG given.
      - LDAP_HOST=auth
      - VIRTUAL_TRANSPORT=lmtp:app:2003
      - LDAP_USER_BASE=ou=${LDAP_USEROU-users},${LDAP_BASE-dc=example,dc=com}
      - LDAP_QUERY_FILTER_USER=(&(objectclass=${LDAP_USEROBJ-posixAccount})(mail=%s))
    volumes:
      - mta:/srv
      - app-spam:/var/lib/kopano/spamd          # kopano-spamd integration
      - /etc/localtime:/etc/localtime:ro        # Use host timezone
    cap_add: # helps debugging by allowing strace
      - sys_ptrace

  db:
    image: mariadb
    command: ['--log_warnings=1']
    networks:
      - backend
    environment:
      - LANG=C.UTF-8
      - MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD-secret}
      - MYSQL_DATABASE=${MYSQL_DATABASE-kopano}
      - MYSQL_USER=${MYSQL_USER-kopano}
      - MYSQL_PASSWORD=${MYSQL_PASSWORD-secret}
    volumes:
      - db:/var/lib/mysql
      - /etc/localtime:/etc/localtime:ro        # Use host timezone

  auth:
    image: mlan/openldap
    networks:
      - backend
    environment:
      - LDAP_LOGLEVEL=parse
    volumes:
      - auth:/srv
      - /etc/localtime:/etc/localtime:ro        # Use host timezone

networks:
  backend:

volumes:
  app-atch:
  app-conf:
  app-spam:
  app-sync:
  auth:
  db:
  mta:
```

## Demo

This repository contains a [demo](demo) directory which hold the [docker-compose.yml](demo/docker-compose.yml) file as well as a [Makefile](demo/Makefile) which might come handy. Start with cloning the [github](https://github.com/mlan/docker-kopano) repository.

```bash
git clone https://github.com/mlan/docker-kopano.git
```

From within the [demo](demo) directory you can start the containers by typing:

```bash
make init
```

Then you can assess WebApp on the URL [`http://localhost:8008`](http://localhost:8008) and log in with the user name `demo` and password `demo` . You can send yourself a test email by typing:

```bash
make web
```

You can send yourself a test email by typing:

```bash
make test
```

When you are done testing you can destroy the test containers by typing

```bash
make destroy
```

## Persistent storage

By default, docker will store the user data and service configurations within the container. This has the drawback that the user data and service configurations are lost together with the container should it be deleted. It can therefore be a good idea to use docker volumes and mount the run directories and/or the configuration directories there so that the data will survive a container deletion.

There are at least three directories which should be considered for persistent storage; the configuration files, `/etc/kopano`, the mail attachments, if they are kept in files, `/var/lib/kopano/attachments` and the active sync device states, if they are kept in files, `/var/lib/z-push`.

## Configuration / seeding procedure

The `mlan/kopano` image contains an elaborate configuration / seeding procedure. The configuration is controlled by environment variables, described below.

The seeding procedure will leave any existing configuration untouched. This is achieved by the using an unlock file: `DOCKER_UNLOCK_FILE=/etc/kopano/.docker.unlock`.
During the image build this file is created. When the the container is started the configuration / seeding procedure will be executed if the `DOCKER_UNLOCK_FILE` can be found. Once the procedure completes the unlock file is deleted preventing the configuration / seeding procedure to run when the container is restarted.

The unlock file approach was selected since it is difficult to accidentally _create_ a file.

In the rare event that want to modify the configuration of an existing container you can override the default behavior by setting `FORCE_CONFIG=overwrite` to a no-empty string.

## Environment variables

When you create the `mlan/kopano` container, you can adjust the configuration of the Kopano server by passing one or more environment variables or on the docker run command line. Note that any pre-existing configuration files within the container will be left untouched.

To see all available configuration variables you can run `man` within the container by for example using the [Makefile](demo/Makefile) described above:

```bash
make mail-app-man_server
```

If you do, you will notice that configuration variable names are all lower case, but they will be matched with all uppercase environment variables by the container `docker-entrypoint.sh` script.

## SQL database configuration

The Kopano server uses a SQL database, which needs to be initiated, see below. Once the SQL database has been initiated you can create the Kopano container and configure it to use the SQL database using environment variables.

#### `MYSQL_HOST`

The host name of the MySQL server to use. Default `MYSQL_HOST=localhost`.

#### `MYSQL_PORT`

The port of the MySQL server to use. Default `MYSQL_PORT=3306`

#### `MYSQL_USER`

The user under which we connect with MySQL. Default `MYSQL_USER=root`. For security reasons it is probably wise not to use the `root` user. Use the same name as was used when initiating the SQL database, see below.

#### `MYSQL_PASSWORD`

The password to use for MySQL. It is possible to leave it empty for no password, but that is advised against. Default `MYSQL_PASSWORD=`. Use the same password as was used when initiating the SQL database, see below.

#### `MYSQL_DATABASE`

The MySQL database to connect to. Default `MYSQL_DATABASE=kopano`. Use the same database name as was used when initiating the SQL database, see below.

#### `ATTACHMENT_STORAGE`

The location where attachments are stored. This can be in the MySQL database, or as separate files. The drawback of `database` is that the large data of attachment will push useful data from the MySQL cache. The drawback of separate files is that a `mysqldump` is not enough for a full disaster recovery. Possible values: `database`, `files`, `files_v2` (experimental). Default: `ATTACHMENT_STORAGE=files`

#### `ATTACHMENT_COMPRESSION`

When the `ATTACHMENT_STORAGE` option is `ATTACHMENT_STORAGE=files`, this option controls the compression level for the attachments. Higher compression levels will compress data better, but at the cost of CPU usage. Lower compression levels will require less CPU but will compress data less. Setting the compression level to 0 will effectively disable compression completely. Changing the compression level, or switching it on or off, will not affect any existing attachments, and will remain accessible as normal. Set to 0 to disable compression completely. The maximum compression level is 9. Default: `ATTACHMENT_COMPRESSION=6`

### SQL Database initialization

When creating the SQL container you can use environment variables to initiate it. For example, `MYSQL_ROOT_PASSWORD=topsecret`, `MYSQL_DATABASE=kopano`, `MYSQL_USER=kopano` and `MYSQL_PASSWORD=verysecret`.

## User authentication `USER_PLUGIN`

Kopano supports three different ways to manage user authentication. Use the `USER_PLUGIN` environment variable to select the source of the user base. Possible values are: `db` (default), `ldap` and `unix`.

 `db`: Retrieve the users from the Kopano database. Use the kopano-admin tool to create users and groups. There are no additional settings for this plug-in.

`ldap`: Retrieve the users and groups information from an LDAP server. All additional LDAP settings are needed see below

`unix`: Retrieve the users and groups information from the Linux password files. This option is probably not interesting here.

### LDAP authentication

An LDAP server with user accounts configured to be used with Kopano is needed, but how to set one up is out of our scope here, instead see: [Kopano Knowledge Base/Install and optimize OpenLDAP for use with Kopano Groupware Core](https://kb.kopano.io/display/WIKI/Install+and+optimize+OpenLDAP+for+use+with+Kopano+Groupware+Core).

Once the LDAP server is up and running, the `mlan/kopano` container can be configured to use it using environment variables. In addition to the variables discussed below also set `USER_PLUGIN=ldap`.

#### `LDAP_URI`

Specifies the URI of one or more LDAP server(s) to use, without any DN portion, such as `ldap://server:389/`, `ldaps://server:636/` or `ldapi:///`. Defaults: `LDAP_URI=ldap://localhost:389/`.

The historic directives `LDAP_HOST`, `LDAP_PORT`, `LDAP_PROTOCOL` are no longer supported (8.7.85).

#### `LDAP_SEARCH_BASE`

This is the subtree entry where all objects are defined in the LDAP server. Default: `LDAP_SEARCH_BASE=dc=kopano,dc=com`

#### `LDAP_USER_TYPE_ATTRIBUTE_VALUE`

This variable determines what defines a valid Kopano user. Default: `LDAP_USER_TYPE_ATTRIBUTE_VALUE=posixAccount`

#### `LDAP_GROUP_TYPE_ATTRIBUTE_VALUE`

This variable determines what defines a valid Kopano group. Default: `LDAP_GROUP_TYPE_ATTRIBUTE_VALUE=posixGroup`

#### `LDAP_USER_SEARCH_FILTER`

Adds an extra filter to the user search. Default `LDAP_USER_SEARCH_FILTER=`

Hint: Use the `kopanoAccount` attribute in the filter to differentiate between non-kopano and kopano users.

## Enabling IMAP, POP3 and ICAL

By default the [IMAP](https://www.atmail.com/blog/imap-commands/) and POP3 services are disabled for all users. Set the environment variable `DISABLED_FEATURES=` to an empty string to enable both IMAP and POP3 for all users.

#### `DISABLED_FEATURES`

The environment variable `DISABLED_FEATURES` take a space separated list of features. Currently it may contain the following features: `imap`, `mobile`, `outlook`, `pop3` and `webapp`. Default: `DISABLED_FEATURES="imap pop3"`

#### `IMAP_LISTEN`, `POP3_LISTEN`and `ICAL_LISTEN`

By default the kopano-gateway and kopano-ical services are configured to only listen on the loop-back interface. To be able to access these services we need them to listen to any interface. This is achieved by setting `IMAP_LISTEN=*:143`, `POP3_LISTEN=*:110` and `ICAL_LISTEN=*:8080`. These port numbers can be changed if desired.

## Enabling IMAPS, POP3S and ICALS

By default the secure protocols are not enabled.

#### `IMAPS_LISTEN`, `POP3S_LISTEN`and `ICALS_LISTEN`

To enable secure access we need to explicitly define their listening ports. This is achieved by setting any combination of `IMAPS_LISTEN=*:993`, `POP3S_LISTEN=*:995` and `ICALS_LISTEN=*:8443`. These port numbers can be changed if desired.

If any of `IMAPS_LISTEN`, `POP3S_LISTEN` and `ICALS_LISTEN` are explicitly defined but there are no certificate files defined, a self-signed certificate will be generated  when the container is created.

### SSL/LTS certificate and private key

For most deployments a trusted SSL/TLS certificate is desired. During startup the `mlan/kopano` looks for [RSA](https://en.wikipedia.org/wiki/RSA_(cryptosystem)) [PEM](https://en.wikipedia.org/wiki/Privacy-Enhanced_Mail) certificate and private key with these specific names: `/etc/kopano/ssl/cert.pem` and `/etc/kopano/ssl/priv_key.pem`. If found they will used by the secure protocols IMAPS, POP3S and ICALS. Moreover the file ownership will be changed if needed to make them readable by the Kopano services.

#### `SSL_CERTIFICATE_FILE` and `SSL_PRIVATE_KEY_FILE`

If you use other file names or directories, you let the Kopano services know by setting the variables `SSL_CERTIFICATE_FILE=/etc/kopano/ssl/cert.pem` and `SSL_PRIVATE_KEY_FILE=/etc/kopano/ssl/priv_key.pem` on the `docker run` command line or in the `docker-compose.yml` file.

For testing purposes you can create a self-signed certificate using the `openssl` utility, see below. Note that this is not necessary since, when secure protocols are defined, a self-signed certificate and private key will be automatically be created during container startup if they are not found.

```bash
openssl genrsa -out ssl/priv_key.pem
openssl req -x509 -utf8 -new -batch -subj "/CN=app" -key ssl/priv_key.pem -out ssl/cert.pem
```

One way to allow the container to read the certificate and private key is to bind mount the host directory holding the files to the container:

```bash
docker run -d -name app -v $pwd/ssl:/etc/kopano/ssl mlan/kopano
```

A other way is to copy them to the container:

```bash
docker create -name app mlan/kopano
docker cp ssl/. app:/etc/kopano/ssl
docker start app
```

If you copy the files to a running container you need to make sure that the user `kopano` can read them.

### Let’s Encrypt LTS certificates using [Traefik](https://docs.traefik.io/)

[Let’s Encrypt](https://letsencrypt.org/) provide free, automated, authorized certificates when you can demonstrate control over your domain. [Automatic Certificate Management Environment (ACME)](https://en.wikipedia.org/wiki/Automated_Certificate_Management_Environment) is the protocol used for such demonstration. There are many agents and applications that supports ACME, e.g., [certbot](https://certbot.eff.org/). The reverse proxy [Traefik](https://docs.traefik.io/) also supports ACME.

#### `ACME_FILE`, `ACME_POSTHOOK`

The `mlan/kopano` image looks for a file `ACME_FILE=/acme/acme.json` at container startup and every time this file changes certificates within this file are extracted. If the host or domain name of one of those certificates matches `HOSTNAME=$(hostname)` or `DOMAIN=${HOSTNAME#*.}` it will be used by the secure protocols.

Once the certificates and keys have been updated, we run the command in the environment variable `ACME_POSTHOOK="sv restart kopano-gateway kopano-ical"`. Kopano services needs to be restarted to update the LTS parameters. If such automatic reloading is not desired, set `ACME_POSTHOOK=` to empty.

So reusing certificates from Traefik will work out of the box if the `/acme` directory in the Traefik container is also mounted in the `mlan/kopano` container.

```bash
docker run -d -name proxy -v proxy-acme:/acme traefik
docker run -d -name app -v proxy-acme:/acme:ro mlan/kopano
```

Note, if the target certificate Common Name (CN) or Subject Alternate Name (SAN) is changed the container needs to be restarted.

Moreover, do not set any of `SSL_CERTIFICATE_FILE` and `SSL_PRIVATE_KEY_FILE` when using `ACME_FILE`.

## Logging `SYSLOG_LEVEL`, `LOG_LEVEL`

The level of output for logging is in the range from 0 to 7. The default is: `SYSLOG_LEVEL=5`.

| emerg | alert | crit | err  | warning | notice | info | debug |
| ----- | ----- | ---- | ---- | ------- | ------ | ---- | ----- |
| 0     | 1     | 2    | 3    | 4       | **5**  | 6    | 7     |

Separately, `LOG_LEVEL` controls the logging level of the Kopano services. `LOG_LEVEL` takes valued from 0 to 6, where the default is `LOG_LEVEL=3`.

| none | crit | err  | warning | notice | info | debug |
| ---- | ---- | ---- | ------- | ------ | ---- | ----- |
| 0    | 1    | 2    | **3**   | 4      | 5    | 6     |

## Custom themes

You can easily customize the Kopano WebApp see [New! JSON themes in Kopano WebApp](https://kopano.com/blog/new-json-themes-in-kopano-webapp/). Once you have the files you can install them in your docker container using the receipt below, where we assume that the container name is `mail-app` and that the directory `mytheme` contains the `theme.json` and the other file defining the theme.

```bash
docker cp mytheme/. mail-app:/etc/kopano/theme/Custom
docker exec -it mail-app chown -R root: /etc/kopano/theme
docker exec -it mail-app run dc_replace /etc/kopano/webapp/config.php 'define("THEME", \x27\x27);' 'define("THEME", \x27Custom\x27);'
```

Please note that it is not possible to rename the directory `/etc/kopano/theme/Custom` within the container without further modifications.

## Mail transfer agent interaction

Environment variables can be used to configure where Kopano find the Mail Transfer Agent, such as Postfix. Likewise the Mail Transfer Agent need to know where to forward emails to.

#### `LMTP_LISTEN`

Added support (release 1.1.3) of the environment variable with default `LMTP_LISTEN=*:2003`, due to misconfiguration of `kopano-dagent` in recent releases (kopano-core 8.7.84).

#### `SMTP_SERVER`

Host name or IP address of the outgoing SMTP server. This server needs to relay mail for your server. Default: `SMTP_SERVER=localhost`

#### `SMTP_PORT`

TCP Port number used to contact the `SMTP_SERVER`. Default: `SMTP_PORT=25`

### Configuring postfix

The Kopano server listens to the port 2003 and expect the [LMTP](https://en.wikipedia.org/wiki/Local_Mail_Transfer_Protocol) protocol. For Postfix you can define `VIRTUAL_TRANSPORT=lmtp:mail-app:2003` assuming the `mlan/kopano` container is named `mail-app`

## Kopano-spamd integration with [mlan/postfix-amavis](https://github.com/mlan/docker-postfix-amavis)

[Kopano-spamd](https://kb.kopano.io/display/WIKI/Kopano-spamd) allow users to
drag messages into the Junk folder triggering the anti-spam filter to learn it as spam. If the user moves the message back to the inbox,
the anti-spam filter will unlearn it.

To allow kopano-spamd integration the kopano and postfix-amavis containers need to
share the `/var/lib/kopano/spamd` folder. If this directory exists within the
postfix-amavis container, the spamd-spam and spamd-ham service will be started.
They will run `sa-learn --spam` or `sa-learn --ham`,
respectively when a message is placed in either `var/lib/kopano/spamd/spam` or
`var/lib/kopano/spamd/ham`.

## Migrate old configuration to newer version of Kopano

Sometimes a new version of Kopano breaks compatibility with old configurations. The `mlan/kopano` include some functionality to address such situations. Use`MIGRATE_CONFIG` to try to attempt all or a list of available fixes. `MIGRATE_CONFIG=1 2 3` is an example of a list of fixes and `MIGRATE_CONFIG=all`  attempts all fixes.

### `MIGRATE_CONFIG=1` Rejected insecure request as configuration for SECURE_COOKIES is true

Prior to Kopano WebApp version 5.0.0 the parameter was `define("INSECURE_COOKIES", true);` was used to allow HTTP access. Now [`define("SECURE_COOKIES", false);`](https://documentation.kopano.io/webapp_admin_manual/config.html#secure-cookies) is used instead. This fix tries to update the configuration accordingly.

# Knowledge base

Here some topics relevant for arranging a mail server are presented.

## Kopano WebApp HTTP access

The distribution installation of `kopano-webapp` only allow HTTPS access. The `mlan/kopano` image updates the configuration to [`define("SECURE_COOKIES", false);`](https://documentation.kopano.io/webapp_admin_manual/config.html#secure-cookies) in `/etc/kopano/webapp/config.php` also allowing HTTP access. This can be useful when arranging the `mlan/kopano` container behind a reverse proxy, like [Traefik](https://doc.traefik.io/traefik/), which then does the enforcement of HTTPS. Also see [`MIGRATE_CONFIG=1` Rejected insecure request as configuration for SECURE_COOKIES is true](#migrate_config=1-rejected-insecure-request-as-configuration-for-secure_cookies-is-true).

## Mail client configuration

### Microsoft Outlook

Kopano, using [Z-Push](http://z-push.org/), allows native interfacing with Microsoft Outlook 2013 and above via the [Exchange ActiveSync (EAS)](https://en.wikipedia.org/wiki/Exchange_ActiveSync) protocol, providing synchronization of mail, calendar, tasks and contacts. For details please see [Configuring Outlook](https://documentation.kopano.io/user_manual_kopanocore/configure_outlook.html).

It can be interesting to know that there is a [Kopano OL Extension](https://kb.kopano.io/display/WIKI/Setting+up+the+Kopano+OL+Extension) that can improve productivity. To install it [download](https://download.kopano.io/community/olextension%3A/) and run the `KopanoOLExtension-<version>-combined.exe` file on your Windows PC.

### Mobile devices

Most mobile devices, that is, Apple iOS, Android and Blackberry have support for [Exchange ActiveSync (EAS)](https://en.wikipedia.org/wiki/Exchange_ActiveSync), providing synchronization of mail, calendar, tasks and contacts. For details please see [Configuring Mobile Devices](https://documentation.kopano.io/user_manual_kopanocore/configure_mobile_devices.html).

### Alternative mail synchronization

Some clients does not support [Exchange ActiveSync (EAS)](https://en.wikipedia.org/wiki/Exchange_ActiveSync), e.g., Linux ones, in which case either the [IMAP](https://en.wikipedia.org/wiki/Internet_Message_Access_Protocol) or [POP3](https://en.wikipedia.org/wiki/Post_Office_Protocol) protocol are used via the Kopano gateway. These protocols only handle incoming mail, so for sending mail clients need to interface directly with a [Mail Transfer Agent (MTA)](https://en.wikipedia.org/wiki/Message_transfer_agent) over [SMTP](https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol). For more details please see [Configuring Alternative Mail Clients](https://documentation.kopano.io/user_manual_kopanocore/configure_alternative_mail_clients.html).

Please note that IMAP and POP3 access are not enabled by default, see [Enabling IMAP and POP3 `DISABLED_FEATURES`](#enabling-imap-and-pop3-disabled_features).

### Alternative calendar synchronization

CalDAV offers calendar sync For more details please see [Configuring CalDAV Clients](https://documentation.kopano.io/user_manual_kopanocore/configure_caldav_clients.html).

### Mozilla Thunderbird

Thunderbird does not support [Exchange ActiveSync (EAS)](https://en.wikipedia.org/wiki/Exchange_ActiveSync), so either [IMAP](https://en.wikipedia.org/wiki/Internet_Message_Access_Protocol) or [POP3](https://en.wikipedia.org/wiki/Post_Office_Protocol) and SMTP is needed to synchronize mail, see [Alternative mail synchronization](#alternative-mail-synchronization).

To synchronize calendar, tasks and contacts CalDAV can be used. Interestingly Thunderbird has a add-on that provides calendar, tasks and contacts synchronization using [Exchange ActiveSync (EAS)](https://en.wikipedia.org/wiki/Exchange_ActiveSync), but not for mail. For details please see [Provider for Exchange ActiveSync](https://addons.thunderbird.net/en-US/thunderbird/addon/eas-4-tbsync/).

# Implementation

Here some implementation details are presented.

## Container init scheme

The container use [runit](http://smarden.org/runit/), providing an init scheme and service supervision, allowing multiple services to be started. There is a Gentoo Linux [runit wiki](https://wiki.gentoo.org/wiki/Runit).

When the container is started, execution is handed over to the script [`docker-entrypoint.sh`](src/docker/bin/docker-entrypoint.sh). It has 4 stages; 0) *register* the SIGTERM [signal (IPC)](https://en.wikipedia.org/wiki/Signal_(IPC)) handler, which is programmed to run all exit scripts in `/etc/docker/exit.d/` and terminate all services, 1) *run* all entry scripts in `/etc/docker/entry.d/`, 2) *start* services registered in `SVDIR=/etc/service/`, 3) *wait* forever, allowing the signal handler to catch the SIGTERM and run the exit scripts and terminate all services.

The entry scripts are responsible for tasks like, seeding configurations, register services and reading state files. These scripts are run before the services are started.

There is also exit script that take care of tasks like, writing state files. These scripts are run when docker sends the SIGTERM signal to the main process in the container. Both `docker stop` and `docker kill --signal=TERM` sends SIGTERM.

## Build assembly

The entry and exit scripts, discussed above, as well as other utility scrips are copied to the image during the build phase. The source file tree was designed to facilitate simple scanning, using wild-card matching, of source-module directories for files that should be copied to image. Directory names indicate its file types so they can be copied to the correct locations. The code snippet in the `Dockerfile` which achieves this is show below.

```dockerfile
COPY	src/*/bin $DOCKER_BIN_DIR/
COPY	src/*/entry.d $DOCKER_ENTRY_DIR/
```

There is also a mechanism for excluding files from being copied to the image from some source-module directories. Source-module directories to be excluded are listed in the file [`.dockerignore`](https://docs.docker.com/engine/reference/builder/#dockerignore-file). Since we don't want files from the module `notused` we list it in the `.dockerignore` file:

```sh
src/notused
```