Usage & Examples

mailcow UI configuration

Several configuration parameters of the mailcow UI can be changed by creating a file data/web/inc/vars.local.inc.php which overrides defaults settings found in data/web/inc/vars.inc.php.

The local configuration file is persistent over updates of mailcow. Try not to change values inside data/web/inc/vars.inc.php, but use them as template for the local override.

mailcow UI configuration parameters can be to...

  • ...change the default language*
  • ...change the default bootstrap theme
  • ...set a password complexity regex
  • ...add mailcow app buttons to the login screen
  • ...set a pagination trigger
  • ...set action after submitting forms (stay in form, return to previous page)

* To change SOGos default language, you will need to edit data/conf/sogo/sogo.conf and replace "English" by your preferred language.

Anonymize headers

Save as data/conf/postfix/mailcow_anonymize_headers.pcre:

/^\s*Received:[^\)]+\)\s+\(Authenticated sender:(.+)/
    REPLACE Received: from localhost (localhost []) (Authenticated sender:$1
/^\s*User-Agent/        IGNORE
/^\s*X-Enigmail/        IGNORE
/^\s*X-Mailer/          IGNORE
/^\s*X-Originating-IP/  IGNORE
/^\s*X-Forward/         IGNORE

Add this to data/conf/postfix/main.cf:

smtp_header_checks = pcre:/opt/postfix/conf/mailcow_anonymize_headers.pcre

Backup and restore maildir (simple tar file)


This line backups the vmail directory to a file backup_vmail.tar.gz in the mailcow root directory:

cd /path/to/mailcow-dockerized
source mailcow.conf
DATE=$(date +"%Y%m%d_%H%M%S")
docker run --rm -it -v $(docker inspect --format '{{ range .Mounts }}{{ if eq .Destination "/var/vmail" }}{{ .Name }}{{ end }}{{ end }}' $(docker-compose ps -q dovecot-mailcow)):/vmail -v ${PWD}:/backup debian:jessie tar cvfz /backup/backup_vmail.tar.gz /vmail

You can change the path by adjusting ${PWD} (which equals to the current directory) to any path you have write-access to. Set the filename backup_vmail.tar.gz to any custom name, but leave the path as it is. Example: [...] tar cvfz /backup/my_own_filename_.tar.gz


cd /path/to/mailcow-dockerized
source mailcow.conf
DATE=$(date +"%Y%m%d_%H%M%S")
docker run --rm -it -v $(docker inspect --format '{{ range .Mounts }}{{ if eq .Destination "/var/vmail" }}{{ .Name }}{{ end }}{{ end }}' $(docker-compose ps -q dovecot-mailcow)):/vmail -v ${PWD}:/backup debian:jessie tar xvfz /backup/backup_vmail.tar.gz

Docker Compose Bash completion

For the tab-tab... :-)

curl -L https://raw.githubusercontent.com/docker/compose/$(docker-compose version --short)/contrib/completion/bash/docker-compose -o /etc/bash_completion.d/docker-compose

Black and Whitelist

Edit a domain as (domain) administrator to add an item to the filter table.

Beware that a mailbox user can login to mailcow and override a domain policy filter item.

Customize Dockerfiles

Make your changes in data/Dockerfiles/$service and build the image locally:

docker build data/Dockerfiles/service -t mailcow/$service

Now auto-recreate modified containers:

docker-compose up -d

Disable sender addresses verification

This option is not best-practice and should only be implemented when there is no other option available to archive whatever you are trying to do.

Simply create a file data/conf/postfix/check_sasl_access and enter the following content. This user must exist in your installation and needs to authenticate before sending mail.

user-to-allow-everything@example.com OK

Open data/conf/postfix/main.cf and find smtpd_sender_restrictions. Prepend check_sasl_access hash:/opt/postfix/conf/check_sasl_access like this:

smtpd_sender_restrictions = check_sasl_access hash:/opt/postfix/conf/check_sasl_access reject_authenticated_sender_login_mismatch [...]

Run postmap on check_sasl_access:

docker-compose exec postfix-mailcow postmap /opt/postfix/conf/check_sasl_access

Restart the Postfix container.

Install Roundcube

Download Roundcube 1.3.x (beta at the time of Feb 2017) to the web htdocs directory and extract it (here rc/):

cd data/web/rc
wget -O - https://github.com/roundcube/roundcubemail/releases/download/1.3-beta/roundcubemail-1.3-beta-complete.tar.gz | tar xfvz -
# Change folder name
mv roundcubemail-1.3* rc
# Change permissions
chown -R root: rc/

Create a file data/web/rc/config/config.inc.php with the following content.

Change the des_key parameter to a random value. It is used to temporarily store your IMAP password.

if (!file_exists('/tmp/mime.types')) {
file_put_contents("/tmp/mime.types", fopen("http://svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types", 'r'));
$config = array();
$config['db_dsnw'] = 'mysql://' . getenv('DBUSER') . ':' . getenv('DBPASS') . '@mysql/' . getenv('DBNAME');
$config['default_host'] = 'tls://dovecot';
$config['default_port'] = '143';
$config['smtp_server'] = 'tls://postfix';
$config['smtp_port'] = 587;
$config['smtp_user'] = '%u';
$config['smtp_pass'] = '%p';
$config['support_url'] = '';
$config['product_name'] = 'Roundcube Webmail';
$config['des_key'] = 'rcmail-!24ByteDESkey*Str';
$config['log_dir'] = '/dev/null';
$config['temp_dir'] = '/tmp';
$config['plugins'] = array(
$config['skin'] = 'larry';
$config['mime_types'] = '/tmp/mime.types';
$config['imap_conn_options'] = array(
'ssl' => array('verify_peer' => false, 'verify_peer_name' => false, 'allow_self_signed' => true)
$config['enable_installer'] = false;
$config['smtp_conn_options'] = array(
'ssl' => array('verify_peer' => false, 'verify_peer_name' => false, 'allow_self_signed' => true)

Point your browser to https://myserver/rc/installer and follow the instructions. Initialize the database and leave the installer.

Delete the directory data/web/rc/installer after a successful installation!

Enable change password function in Roundcube

Open data/web/rc/config/config.inc.php and enable the password plugin:

$config['plugins'] = array(

Open data/web/rc/plugins/password/password.php, search for case 'ssha': and add above:

        case 'ssha256':
            $salt = rcube_utils::random_bytes(8);
            $crypted = base64_encode( hash('sha256', $password . $salt, TRUE ) . $salt );
            $prefix  = '{SSHA256}';

Open data/web/rc/plugins/password/config.inc.php and change the following parameters (or add them at the bottom of that file):

$config['password_driver'] = 'sql';
$config['password_algorithm'] = 'ssha256';
$config['password_algorithm_prefix'] = '{SSHA256}';
$config['password_query'] = "UPDATE mailbox SET password = %P WHERE username = %u";



source mailcow.conf
docker-compose exec mysql-mailcow mysql -u${DBUSER} -p${DBPASS} ${DBNAME}


cd /path/to/mailcow-dockerized
source mailcow.conf
DATE=$(date +"%Y%m%d_%H%M%S")
docker-compose exec mysql-mailcow mysqldump --default-character-set=utf8mb4 -u${DBUSER} -p${DBPASS} ${DBNAME} > backup_${DBNAME}_${DATE}.sql


cd /path/to/mailcow-dockerized
source mailcow.conf
docker-compose exec mysql-mailcow mysql -u${DBUSER} -p${DBPASS} ${DBNAME} < backup_file.sql

Reset MySQL passwords

Stop the stack by running docker-compose stop.

When the containers came to a stop, run this command:

docker-compose run --rm --entrypoint '/bin/sh -c "gosu mysql mysqld --skip-grant-tables & sleep 10 && mysql -hlocalhost -uroot && exit 0"' mysql-mailcow

1. Find database name

MariaDB [(none)]> show databases;
| Database           |
| information_schema |
| mailcow_database   | <=====
| mysql              |
| performance_schema |
4 rows in set (0.00 sec)

2. Reset one or more users

Both "password" and "authentication_string" exist. Currently "password" is used, but better set both.

MariaDB [(none)]> SELECT user FROM mysql.user;
| user         |
| mailcow_user | <===== 
| root         |
2 rows in set (0.00 sec)

MariaDB [(none)]> UPDATE mysql.user SET authentication_string = PASSWORD('gotr00t'), password = PASSWORD('gotr00t') WHERE User = 'root' AND Host = '%';
MariaDB [(none)]> UPDATE mysql.user SET authentication_string = PASSWORD('mookuh'), password = PASSWORD('mookuh') WHERE User = 'mailcow' AND Host = '%';


You can use docker-compose logs $service-name for all containers.

Run docker-compose logs for all logs at once.

Follow the log output by running docker-compose with logs -f.

Limit the output by calling logs with --tail=300 like docker-compose logs --tail=300 mysql-mailcow.

Redirect port 80 to 443

Since February the 28th 2017 mailcow does come with port 80 and 443 enabled.

Open mailcow.conf and set HTTP_BIND=

Open data/conf/nginx/site.conf and add a new "catch-all" site at the top of that file:

server {
    listen 80 default_server;
    include /etc/nginx/conf.d/server_name.active;
    return 301 https://$host$request_uri;

Restart the stack, changed containers will be updated:

docker-compose up -d



docker-compose exec redis-mailcow redis-cli

Remove persistent data

  • Remove volume mysql-vol-1 to remove all MySQL data.
  • Remove volume redis-vol-1 to remove all Redis data.
  • Remove volume vmail-vol-1 to remove all contents of /var/vmail mounted to dovecot-mailcow.
  • Remove volume dkim-vol-1 to remove all DKIM keys.
  • Remove volume rspamd-vol-1 to remove all Rspamd data.

Running docker-compose down -v will destroy all mailcow: dockerized volumes and delete any related containers.

Reset admin password

Reset mailcow admin to admin:moohoo:

cd mailcow_path
bash reset_admin.sh


Learn spam and ham

Rspamd learns mail as spam or ham when you move a message in or out of the junk folder to any mailbox besides trash. This is archived by using the Dovecot plugin "antispam" and a simple parser script.

Rspamd also auto-learns mail when a high or low score is detected (see https://rspamd.com/doc/configuration/statistic.html#autolearning)

The bayes statistics are written to Redis as keys BAYES_HAM and BAYES_SPAM.

You can also use Rspamd's web ui to learn ham and/or spam.

Learn ham or spam from existing directory

You can use a one-liner to learn mail in plain-text (uncompressed) format:

# Ham
for file in /my/folder/cur/*; do docker exec -i $(docker-compose ps -q rspamd-mailcow) rspamc learn_ham < $file; done
# Spam
for file in /my/folder/.Junk/cur/*; do docker exec -i $(docker-compose ps -q rspamd-mailcow) rspamc learn_spam < $file; done

Consider attaching a local folder as new volume to rspamd-mailcow in docker-compose.yml and learn given files inside the container. This can be used as workaround to parse compressed data with zcat. Example:

for file in /data/old_mail/.Junk/cur/*; do rspamc learn_spam < zcat $file; done

CLI tools

docker-compose exec rspamd-mailcow rspamc --help
docker-compose exec rspamd-mailcow rspamadm --help

See Rspamd documentation

Adjust service configurations

The most important configuration files are mounted from the host into the related containers:

├── bind9
│   └── named.conf
├── dovecot
│   ├── dovecot.conf
│   ├── dovecot-master.passwd
│   ├── sieve_after
│   └── sql
│       ├── dovecot-dict-sql.conf
│       └── dovecot-mysql.conf
├── mysql
│   └── my.cnf
├── nginx
│   ├── dynmaps.conf
│   ├── site.conf
│   └── templates
│       ├── listen_plain.template
│       ├── listen_ssl.template
│       └── server_name.template
├── pdns
│   ├── pdns_custom.lua
│   └── recursor.conf
├── postfix
│   ├── main.cf
│   ├── master.cf
│   ├── postscreen_access.cidr
│   ├── smtp_dsn_filter
│   └── sql
│       ├── mysql_relay_recipient_maps.cf
│       ├── mysql_tls_enforce_in_policy.cf
│       ├── mysql_tls_enforce_out_policy.cf
│       ├── mysql_virtual_alias_domain_catchall_maps.cf
│       ├── mysql_virtual_alias_domain_maps.cf
│       ├── mysql_virtual_alias_maps.cf
│       ├── mysql_virtual_domains_maps.cf
│       ├── mysql_virtual_mailbox_maps.cf
│       ├── mysql_virtual_relay_domain_maps.cf
│       ├── mysql_virtual_sender_acl.cf
│       └── mysql_virtual_spamalias_maps.cf
├── rmilter
│   └── rmilter.conf
├── rspamd
│   ├── dynmaps
│   │   ├── authoritative.php
│   │   ├── settings.php
│   │   ├── tags.php
│   │   └── vars.inc.php -> ../../../web/inc/vars.inc.php
│   ├── local.d
│   │   ├── dkim.conf
│   │   ├── metrics.conf
│   │   ├── options.inc
│   │   ├── redis.conf
│   │   ├── rspamd.conf.local
│   │   └── statistic.conf
│   ├── lua
│   │   └── rspamd.local.lua
│   └── override.d
│       ├── logging.inc
│       ├── worker-controller.inc
│       └── worker-normal.inc
└── sogo
    ├── sieve.creds
    └── sogo.conf

Just change the according configuration file on the host and restart the related service:

docker-compose restart service-mailcow


Mailbox users can tag their mail address like in me+facebook@example.org and choose between to setups to handle this tag:

1. Move this message to a subfolder "facebook" (will be created lower case if not existing)

2. Prepend the tag to the subject: "[facebook] Subject"

Two-factor authentication

So far two methods for TFA are implemented. Both work with the fantastic Yubikey.

While Yubi OTP needs an active internet connection and an API ID and key, U2F will work with any FIDO U2F USB key out of the box, but can only be used when mailcow is accessed over HTTPS.

Both methods support multiple YubiKeys.

As administrator you are able to temporary disable a domain administrators TFA login until they successfully logged in.

The key used to login will be displayed in green, while other keys remain grey.

Yubi OTP

The Yubi API ID and Key will be checked against the Yubico Cloud API. When setting up TFA you will be asked for your personal API account for this key. The API ID, API key and the first 12 characters (your YubiKeys ID in modhex) are stored in the MySQL table as secret.


Only Google Chrome (+derivates) and Opera support U2F authentication to this day natively. For Firefox you will need to install the "U2F Support Add-on" as provided on mozilla.org.

U2F works without an internet connection.


In order to enable Portainer, the docker-compose.yml and site.conf for nginx must be modified.

1. docker-compose.yml: Insert this block for portainer

      image: portainer/portainer
        - /var/run/docker.sock:/var/run/docker.sock
      restart: always
      dns_search: mailcow-network
            - portainer

2a. data/conf/nginx/site.conf: Just beneath the opening line, at the same level as a server { block, add this:

upstream portainer {
  server portainer-mailcow:9000;

map $http_upgrade $connection_upgrade {
  default upgrade;
  '' close;

2b. data/conf/nginx/site.conf: Then, inside both (ssl and plain) server blocks, add this:

  location /portainer/ {
    proxy_http_version 1.1;
    proxy_set_header Host              $http_host;   # required for docker client's sake
    proxy_set_header X-Real-IP         $remote_addr; # pass on real client's IP
    proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_read_timeout                 900;

    proxy_set_header Connection "";
    proxy_buffers 32 4k;
    proxy_pass http://portainer/;

  location /portainer/api/websocket/ {
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection $connection_upgrade;
    proxy_pass http://portainer/api/websocket/;

Now you can simply navigate to https://${MAILCOW_HOSTNAME}/portainer/ to view your Portainer container monitoring page. You’ll then be prompted to specify a new password for the admin account. After specifying your password, you’ll then be able to connect to the Portainer UI.

Change autodiscover setup type

This disables ActiveSync in the autodiscover service for Outlook and configures it with IMAP and SMTP instead:

Open data/web/autodiscover.php and set 'useEASforOutlook' => 'yes' to 'useEASforOutlook' => 'no'.

To always use IMAP and SMTP instead of EAS, set 'autodiscoverType' => 'imap'.

Why Bind?

For DNS blacklist lookups and DNSSEC.

Most systems use either a public or a local caching DNS resolver. That's a very bad idea when it comes to filter spam using DNS-based blackhole lists (DNSBL) or similar technics. Most if not all providers apply a rate limit based on the DNS resolver that is used to query their service. Using a public resolver like Googles 4x8, OpenDNS or any other shared DNS resolver like your ISPs will hit that limit very soon.