Mailcow-dockerized failing to compose un initial standup

xeonix

I have been trying unsuccessfully to build a new mailcow container on a brand new ubuntu 24.04 server with the official docker/compose binaries. I followed the provided documentation to the letter and the issue i keep having is the mailcow-unbound container has no network access when it comes up. I have tried ubuntu 24.04, 22.04, and Debian 12.9, all of them have the exact same issue.
To expand:
When i do the “docker compose up -d”, the mailcow-unbound never full comes online and has an error. every other supporting container comes up. once it times out and gives an error for the mailcow-unbound container, i then run “docker compose logs -f” and it is literally trying to resolve via dns the mailcow domains and is unsuccessful.
When i go to check the running containers, it looks like the mailcow-network container is not running, which would explain why it is unable to resolve anything.
I’m using the docker-compose.yml as it is literally provided with no changes. I have double checked that the default network that docker is standing up for it (172.22.x.x) does not exist and there is absolutely no overlap in my internal network.
If i do a “docker network inspect mailcow-network” it says it isn’t there.

Please help, i have literally tried to deploy this 7 times on different base os’s and have no idea why this is happening. at this point i am not sure if it is something with my configuration but i feel like i have eliminated the obvious culprits.

DocFraggle

xeonix When i go to check the running containers, it looks like the mailcow-network container is not running

That’s because it’s not a container, it’s a network 😉

You can’t find it because you have the wrong name:

docker network inspect mailcowdockerized_mailcow-network

which you can find out easily by using

docker network ls

Why do you think the unbound container has no network? Because it can’t resolve stuff? This can be due to a firewall like ufw, did you stop and disable that service as the docs state?

Endearing6500

Don’t know if this is relevant.
After an update of docker-ce to 28.0.0 on Ubuntu 22.04.5 aarch64, mailcow-unbound failed to start as it had no external IPv4 connectivity and failed the health check. After some brief troubleshooting, I downgraded docker-ce back to 27.5.1 and everthing came up.

kasimrafique

Thank you Endearing6500! This also happened to me and I could not understand why it suddenly stopped working. All I did was update my server and suddenly unbound would not start and none of the containers could not communicate outside the docker network.

Thought I’d put the commands I ran (Ubuntu 22.04 arm) to downgrade for anyone facing the same problem:

sudo systemctl stop docker
sudo apt remove docker-ce docker-ce-cli

(Note removing docker doesn’t delete the docker volumes)

Then found exact package version using this apt-cache madison docker-ce so I could run…

sudo apt install docker-ce=5:27.5.1-1~ubuntu.22.04~jammy docker-ce-cli=5:27.5.1-1~ubuntu.22.04~jammy