A fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.). Only configuration files, no SQL database. Keep it simple and versioned. Easy to deploy and upgrade.
- [Dovecot](https://www.dovecot.org) for SASL, IMAP (or POP3), with LDAP Auth, Sieve and [quotas](https://github.com/docker-mailserver/docker-mailserver/wiki/Configure-Accounts#mailbox-quota)
- [Setup script](https://github.com/docker-mailserver/docker-mailserver/wiki/Setup-docker-mailserver-using-the-script-setup.sh) to easily configure and maintain your mailserver
- Basic [Sieve support](https://github.com/docker-mailserver/docker-mailserver/wiki/Configure-Sieve-filters) using dovecot
**Note:** You'll need to deactivate some services like ClamAV to be able to run on a host with 512MB of RAM. Even with 1G RAM you may run into problems without swap, see [FAQ](https://github.com/docker-mailserver/docker-mailserver/wiki/FAQ-and-Tips).
The [CI/CD workflows](https://github.com/docker-mailserver/docker-mailserver/actions) automatically build, test and push new images to container registries. Currently, the following registries are supported:
- these files supports [only simple `VAR=VAL`](https://docs.docker.com/compose/env-file/)
- don't quote your values
- variable substitution is *not* supported (e.g. `OVERRIDE_HOSTNAME=$HOSTNAME.$DOMAINNAME`).
- Variables in `.env` are expanded in the `docker-compose.yml` file **only** and **not** in the container. The file `mailserver.env` serves this case where environment variables are used in the container.
- If you want to use a bare domain (host name = domain name), see [FAQ](https://github.com/docker-mailserver/docker-mailserver/wiki/FAQ-and-Tips#can-i-use-nakedbare-domains-no-host-name)
If you'd like to use SELinux, add `-Z` to the variable `SELINUX_LABEL` in `.env`. If you want the volume bind mount to be shared among other containers switch `-Z` to `-z`
If you are using a LDAP setup the setup looks a bit different as you do not add user accounts directly. Therefore `postfix` doesn't know your domain(s) and you need to provide it when configuring `dkim`:
When keys are generated, you can configure your DNS server by just pasting the content of `config/opendkim/keys/domain.tld/mail.txt` to [set up DKIM](https://mxtoolbox.com/dmarc/dkim/setup/how-to-setup-dkim).
If you'd like to change, patch or alter files or behavior of `docker-mailserver`, you can use a script. Just place it the `config/` folder that is created on startup and call it `user-patches.sh`. The setup is done like this:
And you're done. The user patches script runs right before starting daemons. That means, all the other configuration is in place, so the script can make final adjustments.
We are currently providing support for Linux. Windows is _not_ supported and is known to cause problems. Similarly, macOS is _not officially_ supported - but you may get it to work there. In the end, Linux should be your preferred operating system for this image, especially when using this mailserver in production.
#### Support for Multiple Domains
`docker-mailserver` supports multiple domains out of the box, so you can do this:
If you got any problems with SPF and/or forwarding mails, give [SRS](https://github.com/roehling/postsrsd/blob/master/README.md) a try. You enable SRS by setting `ENABLE_SRS=1`. See the variable description for further information.
1. A connection *may* be secured over TLS when both ends support `STARTTLS`. On ports 110, 143 and 587, `docker-mailserver` will reject a connection that cannot be secured. Port 25 is [required](https://serverfault.com/questions/623692/is-it-still-wrong-to-require-starttls-on-incoming-smtp-messages) to support insecure connections.
2. Receives email and filters for spam and viruses. For submitting outgoing mail you should prefer the submission ports(465, 587), which require authentication. Unless a relay host is configured, outgoing email will leave the server via port 25(thus outbound traffic must not be blocked by your provider or firewall).
3. A submission port since 2018, [RFC 8314](https://tools.ietf.org/html/rfc8314). Originally a secure variant of port 25.
See the [wiki](https://github.com/docker-mailserver/docker-mailserver/wiki) for further details and best practice advice, especially regarding security concerns.
This example provides you only with a basic example of what a minimal setup could look like. We **strongly recommend** that you go through the configuration file yourself and adjust everything to your needs. The default [docker-compose.yml](./docker-compose.yml) can be used for the purpose out-of-the-box, see the [usage section](#usage).
