Installation of mailcow¶

Prerequisites¶

System Packages¶

The following Linux packages are required for using mailcow and may need to be installed depending on your distribution:

git
openssl
curl
awk
sha1sum
grep
cut
jq (new as of 2025-08)

Docker and Docker Compose¶

For the installation, you will need:

Docker: Version >= 24.0.0
Docker Compose: Version >= 2.0

Installation guides can be found here:

Quick Installation¶

System Packages¶

Debian/Ubuntu:¶

apt update
apt install -y git openssl curl gawk coreutils grep jq

RHEL-based systems (e.g., Rocky Linux 9):¶

dnf install -y git openssl curl gawk coreutils grep jq

Alpine Linux (e.g., 3.22):¶

apk add --no-cache --upgrade sed findutils bash git openssl curl gawk coreutils grep jq

Note

All programs not explicitly listed in the installation process are already included as subprograms in coreutils.

Docker¶

Important

Use the latest available Docker Engine and not the version from your Linux distribution's package sources.

Debian/Ubuntu:¶

curl -sSL https://get.docker.com/ | CHANNEL=stable sh
systemctl enable --now docker

RHEL-based systems (e.g., Rocky Linux 9):¶

dnf config-manager --add-repo=https://download.docker.com/linux/centos/docker-ce.repo
dnf install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
systemctl enable --now docker

Alpine Linux (e.g., 3.22):¶

apk --no-cache --upgrade add docker
rc-update add docker default
rc-service docker start

Note

The get.docker.com script does not work reliably or at all on RHEL and Alpine Linux systems. Use the manual method instead.

Docker Compose¶

Warning

mailcow requires Docker Compose version >= 2.0.

Installation via Package Manager (Plugin)¶

Note

This method requires that the Docker repository has been added (see Docker).

Debian/Ubuntu:¶

apt update
apt install docker-compose-plugin

RHEL-based systems:¶

dnf update
dnf install docker-compose-plugin

Alpine Linux (e.g., 3.22):¶

apk add --no-cache --upgrade docker-cli-compose

Warning

For the plugin version, the command is docker compose (without a hyphen).

Installation as a Standalone Version¶

LATEST=$(curl -Ls -w %{url_effective} -o /dev/null https://github.com/docker/compose/releases/latest) && \
LATEST=${LATEST##*/} && \
curl -L https://github.com/docker/compose/releases/download/$LATEST/docker-compose-$(uname -s)-$(uname -m) > /usr/local/bin/docker-compose
chmod +x /usr/local/bin/docker-compose

Warning

For the standalone version, the command is docker-compose (with a hyphen).

SELinux Configuration (Optional)¶

On SELinux-enabled systems (e.g., CentOS 7):

Check if the container-selinux package is installed:
```
rpm -qa | grep container-selinux
```
Enable SELinux support in Docker:
- Edit /etc/docker/daemon.json and add "selinux-enabled": true:
```
{
  "selinux-enabled": true
}
```
- Restart the Docker daemon.

For more information, see the container-selinux Readme.

Installing mailcow¶

Clone the repository:

su
umask 0022
cd /opt
git clone https://github.com/mailcow/mailcow-dockerized
cd mailcow-dockerized

Generate the configuration file:
```
./generate_config.sh
```
Adjust the configuration if necessary:
```
nano mailcow.conf
```

Starting mailcow¶

Download the images and start the containers:

Docker Compose (Plugin)Docker Compose (Standalone)

docker compose pull
docker compose up -d

docker-compose pull
docker-compose up -d

Done!

You can now access https://${MAILCOW_HOSTNAME}/admin using the default credentials admin and the password moohoo.

Troubleshooting¶

MTU not equal to 1500 (e.g., OpenStack)¶

Adjust the network settings in docker-compose.yml:

networks:
  mailcow-network:
    driver_opts:
      com.docker.network.driver.mtu: 1450

No IPv6 on the Host System¶

Disable IPv6 for the mailcow network if your host system does not support IPv6. More information can be found here.

Important Notes¶

Data Persistence: Your data is stored in Docker volumes and remains intact even if you recreate or delete containers.
Reverse Proxy: If you are not using a reverse proxy, you should redirect HTTP to HTTPS.