This pages explains how to get started with DMS. The guide uses Docker Compose as a reference. In our examples, a volume mounts the host location [`docker-data/dms/config/`][docs-dms-config-volume] to `/tmp/docker-mailserver/` inside the container.
Before you can get started with deploying your own mail server, there are some requirements to be met:
1. You need to have a host that you can manage.
2. You need to own a domain, and you need to able to manage DNS for this domain.
### Host Setup
There are a few requirements for a suitable host system:
1. The host should have a static IP address; otherwise you will need to dynamically update DNS (undesirable due to DNS caching)
2. The host should be able to send/receive on the [necessary ports for mail][docs-ports-overview]
3. You should be able to set a `PTR` record for your host; security-hardened mail servers might otherwise reject your mail server as the IP address of your host does not resolve correctly/at all to the DNS name of your server.
On the host, you need to have a suitable container runtime (like _Docker_ or _Podman_) installed. We assume [_Docker Compose_][docker-compose] is [installed][docker-compose-installation]. We have aligned file names and configuration conventions with the latest [Docker Compose (currently V2) specification][docker-compose-specification].
The DNS setup is a big and essential part of the whole setup. There is a lot of confusion for newcomers and people starting out when setting up DNS. This section provides an example configuration and supplementary explanation. We expect you to be at least a bit familiar with DNS, what it does and what the individual record types are.
Now let's say you just bought `example.com` and you want to be able to send and receive e-mails for the address `test@example.com`. On the most basic level, you will need to
1. set an `MX` record for your domain `example.com` - in our example, the MX record contains `mail.example.com`
2. set an `A` record that resolves the name of your mail server - in our example, the A record contains `11.22.33.44`
3. (in a best-case scenario) set a `PTR` record that resolves the IP of your mail server - in our example, the PTR contains `mail.example.com`
We will later dig into DKIM, DMARC & SPF, but for now, these are the records that suffice in getting you up and running. Here is a short explanation of what the records do:
- The **MX record** tells everyone which (DNS) name is responsible for e-mails on your domain.
Because you want to keep the option of running another service on the domain name itself, you run your mail server on `mail.example.com`.
This does not imply your e-mails will look like `test@mail.example.com`, the DNS name of your mail server is decoupled of the domain it serves e-mails for.
In theory, you mail server could even serve e-mails for `test@some-other-domain.com`, if the MX record for `some-other-domain.com` points to `mail.example.com`.
- The **A record** tells everyone which IP address the DNS name `mail.example.com` resolves to.
- The **PTR record** is the counterpart of the A record, telling everyone what name the IP address `11.22.33.44` resolves to.
If you setup everything, it should roughly look like this:
```console
$ dig @1.1.1.1 +short MX example.com
mail.example.com
$ dig @1.1.1.1 +short A mail.example.com
11.22.33.44
$ dig @1.1.1.1 +short -x 11.22.33.44
mail.example.com
```
## Deploying the Actual Image
### Tagging Convention
To understand which tags you should use, read this section carefully. [Our CI][github-ci] will automatically build, test and push new images to the following container registries:
!!! danger "Using the Correct Commands For Stopping and Starting DMS"
**Use `docker compose up / down`, not `docker compose start / stop`**. Otherwise, the container is not properly destroyed and you may experience problems during startup because of inconsistent state.
We encourage you to directly use `setup` inside the container (like shown above). If you still want to use `setup.sh`, here's some information about it.
If no DMS container is running, any `./setup.sh` command will check online for the `:latest` image tag (the current _stable_ release), performing a `docker pull ...` if necessary followed by running the command in a temporary container:
On first start, you will need to add at least one email account (unless you're using LDAP). You have two minutes to do so, otherwise DMS will shutdown and restart. You can add accounts by running `docker exec -ti <CONTAINER NAME> setup email add user@example.com`. **That's it! It really is that easy**.
You should add at least one [alias][docs-aliases], the [_postmaster alias_][docs-env-postmaster]. This is a common convention, but not strictly required.
You will very likely want to configure your DNS with these TXT records: [SPF, DKIM, and DMARC][cloudflare-spf-dkim-dmarc]. We also ship a [dedicated page in our documentation][docs-dkim-dmarc-spf] about the setup of DKIM, DMARC & SPF.
If you'd like to change, patch or alter files or behavior of DMS, you can use a script. See [this part of our documentation][docs-user-patches] for a detailed explanation.
