docker-mailserver/README.md

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# Docker Mailserver
[![ci::status]][ci::github] [![docker::pulls]][docker::hub]
[ci::status]: https://img.shields.io/github/workflow/status/docker-mailserver/docker-mailserver/Build%2C%20Test%20%26%20Deploy?color=blue&label=CI&logo=github&logoColor=white&style=for-the-badge
[ci::github]: https://github.com/docker-mailserver/docker-mailserver/actions
[docker::pulls]: https://img.shields.io/docker/pulls/mailserver/docker-mailserver.svg?style=for-the-badge&logo=docker&logoColor=white
[docker::hub]: https://hub.docker.com/r/mailserver/docker-mailserver/
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.
[Why this image was created.](http://tvi.al/simple-mail-server-with-docker/)
1. [Included Services](#included-services)
2. [Issues and Contributing](./CONTRIBUTING.md)
3. [Requirements](#requirements)
4. [Usage](#usage)
5. [Examples](#examples)
6. [Environment Variables](./ENVIRONMENT.md)
7. [Release Notes](./CHANGELOG.md)
## Included Services
- [Postfix](http://www.postfix.org) with SMTP or LDAP auth
- [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)
- [Amavis](https://www.amavis.org/)
- [Spamassasin](http://spamassassin.apache.org/) supporting custom rules
- [ClamAV](https://www.clamav.net/) with automatic updates
- [OpenDKIM](http://www.opendkim.org)
- [OpenDMARC](https://github.com/trusteddomainproject/OpenDMARC)
- [Fail2ban](https://www.fail2ban.org/wiki/index.php/Main_Page)
- [Fetchmail](http://www.fetchmail.info/fetchmail-man.html)
- [Postscreen](http://www.postfix.org/POSTSCREEN_README.html)
- [Postgrey](https://postgrey.schweikert.ch/)
- [LetsEncrypt](https://letsencrypt.org/) and self-signed certificates
- [Setup script](https://github.com/docker-mailserver/docker-mailserver/wiki/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
- SASLauthd with LDAP auth
- Persistent data and state
- [CI/CD](https://github.com/docker-mailserver/docker-mailserver/actions)
- [Extension Delimiters](http://www.postfix.org/postconf.5.html#recipient_delimiter) (`you+extension@example.com` go to `you@example.com`)
## Requirements
**Recommended**:
- 1 Core
- 1-2GB RAM
- Swap enabled for the container
**Minimum**:
- 1 vCore
- 512MB RAM
**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).
## Usage
### Available image sources / tags
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:
- [DockerHub](https://hub.docker.com/repository/docker/mailserver/docker-mailserver)
- [GitHub Container Registry](https://github.com/orgs/docker-mailserver/packages?repo_name=docker-mailserver)
All workflows are using the **tagging convention** listed below. It is subsequently applied to all images pushed to supported container registries:
| Event | Ref | Commit SHA | Image Tags |
|--------------|-----------------------|------------|-------------------------------|
| `push` | `refs/heads/master` | `cf20257` | `edge` |
| `push` | `refs/heads/stable` | `cf20257` | `stable` |
| `push tag` | `refs/tags/1.2.3` | `ad132f5` | `1.2.3`, `1.2`, `1`, `latest` |
| `push tag` | `refs/tags/v1.2.3` | `ad132f5` | `1.2.3`, `1.2`, `1`, `latest` |
### Get the tools
Download the `docker-compose.yml`, `compose.env`, `mailserver.env` and the `setup.sh` files:
``` BASH
wget https://raw.githubusercontent.com/docker-mailserver/docker-mailserver/master/setup.sh
wget https://raw.githubusercontent.com/docker-mailserver/docker-mailserver/master/docker-compose.yml
wget https://raw.githubusercontent.com/docker-mailserver/docker-mailserver/master/mailserver.env
wget -O .env https://raw.githubusercontent.com/docker-mailserver/docker-mailserver/master/compose.env
chmod a+x ./setup.sh
# and make yourself familiar with the script
./setup.sh help
```
### Create a docker-compose environment
- [Install the latest docker-compose](https://docs.docker.com/compose/install/)
- Edit the files `.env` and `mailserver.env` to your liking:
- `.env` contains the configuration for Docker Compose
- `mailserver.env` contains the configuration for the mailserver container
- 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)
### Get up and running
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`
``` BASH
docker-compose up -d mail
# without SELinux
./setup.sh email add <user@domain> [<password>]
./setup.sh alias add postmaster@<domain> <user@domain>
./setup.sh config dkim
# with SELinux
./setup.sh -Z email add <user@domain> [<password>]
./setup.sh -Z alias add postmaster@<domain> <user@domain>
./setup.sh -Z config dkim
```
If you are using a LDAP setup the setup looks a bit different as you do not add user accounts directly. Postfix doesn't know your domain(s) and you need to provide it when configuring DKIM:
``` BASH
./setup.sh config dkim domain '<domain.tld>[,<domain2.tld>]'
```
If you want to see detailed usage information, run `./setup.sh config dkim help`.
### Miscellaneous
#### DNS - 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).
#### Custom user changes & patches
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:
``` BASH
# 1. Either create the config/ directory yourself
# or let docker-mailserver create it on initial
# startup
/where/docker-mailserver/resides/ $ mkdir config && cd config
# 2. Create the user-patches.sh script and make it
# executable
/where/docker-mailserver/resides/config/ $ touch user-patches.sh
/where/docker-mailserver/resides/config/ $ chmod +x user-patches.sh
# 3. Edit it
/where/docker-mailserver/resides/config/ $ vi user-patches.sh
/where/docker-mailserver/resides/config/ $ cat user-patches.sh
#! /bin/bash
# ! THIS IS AN EXAMPLE !
# If you modify any supervisord configuration, make sure
# to run `supervisorctl update` and/or `supervisorctl reload` afterwards.
# shellcheck source=/dev/null
. /usr/local/bin/helper-functions.sh
_notify 'Applying user-patches'
if ! grep -q '192.168.0.1' /etc/hosts
then
echo -e '192.168.0.1 some.domain.com' >> /etc/hosts
fi
```
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.
#### Supported Operating Systems
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:
``` BASH
./setup.sh email add user1@docker.example.com
./setup.sh email add user1@mail.example.de
./setup.sh email add user1@server.example.org
```
#### Updating `docker-mailserver`
``` BASH
docker-compose down
docker pull docker.io/mailserver/docker-mailserver:<VERSION TAG>
docker-compose up -d mailserver
```
You're done! And don't forget to have a look at the remaining functions of the `setup.sh` script with `./setup.sh -h`.
#### SPF/Forwarding Problems
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.
#### Exposed ports
| Protocol | Opt-in Encryption &#185; | Enforced Encryption | Purpose |
| :------: | :----------------------: | :-----------------: | :------------: |
| SMTP | 25 | N/A | Transfer&#178; |
| ESMTP | 587 | 465&#179; | Submission |
| POP3 | 110 | 995 | Retrieval |
| IMAP4 | 143 | 993 | Retrieval |
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.
## Examples
### With Relevant Environmental Variables
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).
``` YAML
version: '3.8'
services:
mailserver:
image: docker.io/mailserver/docker-mailserver:latest
hostname: mail # ${HOSTNAME}
domainname: domain.com # ${DOMAINNAME}
container_name: mail # ${CONTAINER_NAME}
ports:
- "25:25"
- "143:143"
- "587:587"
- "993:993"
volumes:
- maildata:/var/mail
- mailstate:/var/mail-state
- maillogs:/var/log/mail
- ./config/:/tmp/docker-mailserver/
environment:
- ENABLE_SPAMASSASSIN=1
- SPAMASSASSIN_SPAM_TO_INBOX=1
- ENABLE_CLAMAV=1
- ENABLE_FAIL2BAN=1
- ENABLE_POSTGREY=1
- ENABLE_SASLAUTHD=0
- ONE_DIR=1
- DMS_DEBUG=0
cap_add:
- NET_ADMIN
- SYS_PTRACE
restart: always
volumes:
maildata:
mailstate:
maillogs:
```
#### LDAP setup
``` YAML
version: '3.8'
services:
mailserver:
image: docker.io/mailserver/docker-mailserver:latest
hostname: mail # ${HOSTNAME}
domainname: domain.com # ${DOMAINNAME}
container_name: mail # ${CONTAINER_NAME}
ports:
- "25:25"
- "143:143"
- "587:587"
- "993:993"
volumes:
- maildata:/var/mail
- mailstate:/var/mail-state
- maillogs:/var/log/mail
- ./config/:/tmp/docker-mailserver/
environment:
- ENABLE_SPAMASSASSIN=1
- SPAMASSASSIN_SPAM_TO_INBOX=1
- ENABLE_CLAMAV=1
- ENABLE_FAIL2BAN=1
- ENABLE_POSTGREY=1
- ONE_DIR=1
- DMS_DEBUG=0
- ENABLE_LDAP=1
- LDAP_SERVER_HOST=ldap # your ldap container/IP/ServerName
- LDAP_SEARCH_BASE=ou=people,dc=localhost,dc=localdomain
- LDAP_BIND_DN=cn=admin,dc=localhost,dc=localdomain
- LDAP_BIND_PW=admin
- LDAP_QUERY_FILTER_USER=(&(mail=%s)(mailEnabled=TRUE))
- LDAP_QUERY_FILTER_GROUP=(&(mailGroupMember=%s)(mailEnabled=TRUE))
- LDAP_QUERY_FILTER_ALIAS=(|(&(mailAlias=%s)(objectClass=PostfixBookMailForward))(&(mailAlias=%s)(objectClass=PostfixBookMailAccount)(mailEnabled=TRUE)))
- LDAP_QUERY_FILTER_DOMAIN=(|(&(mail=*@%s)(objectClass=PostfixBookMailAccount)(mailEnabled=TRUE))(&(mailGroupMember=*@%s)(objectClass=PostfixBookMailAccount)(mailEnabled=TRUE))(&(mailalias=*@%s)(objectClass=PostfixBookMailForward)))
- DOVECOT_PASS_FILTER=(&(objectClass=PostfixBookMailAccount)(uniqueIdentifier=%n))
- DOVECOT_USER_FILTER=(&(objectClass=PostfixBookMailAccount)(uniqueIdentifier=%n))
- ENABLE_SASLAUTHD=1
- SASLAUTHD_MECHANISMS=ldap
- SASLAUTHD_LDAP_SERVER=ldap
- SASLAUTHD_LDAP_BIND_DN=cn=admin,dc=localhost,dc=localdomain
- SASLAUTHD_LDAP_PASSWORD=admin
- SASLAUTHD_LDAP_SEARCH_BASE=ou=people,dc=localhost,dc=localdomain
- SASLAUTHD_LDAP_FILTER=(&(objectClass=PostfixBookMailAccount)(uniqueIdentifier=%U))
- POSTMASTER_ADDRESS=postmaster@localhost.localdomain
- POSTFIX_MESSAGE_SIZE_LIMIT=100000000
cap_add:
- NET_ADMIN
- SYS_PTRACE
restart: always
volumes:
maildata:
mailstate:
maillogs:
```