tvial/docker-mailserver repository overview

⁠Migration / Deprecation Notice - We Migrated

We have migrated this repository to the Docker Mailserver Organization. This repository is therefore not maintained anymore. Please head over to the new repository⁠ for issues, pull requests and discussions. All work is now done there.

⁠docker-mailserver

A fullstack but simple mail server (SMTP, IMAP, Antispam, Antivirus...). Only configuration files, no SQL database. Keep it simple and versioned. Easy to deploy and upgrade.

Why this image was created.⁠

1. Release Notes⁠
2. Includes⁠
3. Issues & Contributing⁠
4. Requirements⁠
5. Usage⁠
6. Examples⁠
7. Environment Variables⁠

⁠Release Notes

⁠v7.2.0

1. Refactored target/bin/
2. Enhanced and refactored all tests
3. Added Code of Conduct
4. Redesigned environment variable use
5. Added missing Dovecot descriptions

⁠v7.1.0

1. The use of default variables has changed slightly. Consult the environment variables⁠ section
2. New contributing guidelines were added
3. Added coherent coding style and linting
4. Added option to use non-default network interface
5. SELinux is now supported

⁠Includes

• Postfix⁠ with SMTP or LDAP auth
• Dovecot⁠ for SASL, IMAP (and optional POP3) with SSL support, with LDAP auth, Sieve and quotas⁠
• Amavis⁠
• Spamassasin⁠ supporting custom rules
• ClamAV⁠ with automatic updates
• OpenDKIM⁠
• OpenDMARC⁠
• Fail2ban⁠
• Fetchmail⁠
• Postscreen⁠
• Postgrey⁠
• LetsEncrypt⁠ and self-signed certificates
• Setup script⁠ to easily configure and maintain your mailserver
• basic Sieve support⁠ using dovecot
• SASLauthd with LDAP auth
• persistent data and state (but think about backups!)
• Integration tests⁠
• Automated builds on docker hub⁠
• Plus addressing (a.k.a. extension delimiters⁠) works out of the box: email for [email protected] go to [email protected]

⁠Issues & Contributing

Before opening an issue, please have a look this README, the Wiki⁠ and the Postfix/Dovecot documentation.

If you'd like to contribute, read CONTRIBUTING.md⁠ thoroughly.

⁠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.

⁠Usage

⁠Get the tools

Download the docker-compose.yml, compose.env, mailserver.env and the setup.sh files:

wget https://raw.githubusercontent.com/tomav/docker-mailserver/master/setup.sh
wget https://raw.githubusercontent.com/tomav/docker-mailserver/master/docker-compose.yml
wget https://raw.githubusercontent.com/tomav/docker-mailserver/master/mailserver.env
wget -O .env https://raw.githubusercontent.com/tomav/docker-mailserver/master/compose.env

chmod a+x ./setup.sh

⁠Create a docker-compose environment

• Install the latest docker-compose⁠
• 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 lines (see Documentation⁠).
  • Don't quote your values.
  • Variable substitution is not supported (e.g. OVERRIDE_HOSTNAME=$HOSTNAME.$DOMAINNAME).

Note: 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.

Note: If you want to use a bare domain (host name equals domain name) see FAQ⁠.

⁠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

# without SELinux
docker-compose up -d mail

./setup.sh email add <user@domain> [<password>]
./setup.sh alias add postmaster@<domain> <user@domain>
./setup.sh config dkim

# with SELinux
docker-compose up -d mail

./setup.sh -Z email add <user@domain> [<password>]
./setup.sh -Z alias add postmaster@<domain> <user@domain>
./setup.sh -Z config dkim

⁠Miscellaneous

⁠DNS - DKIM

Now that the keys are generated, you can configure your DNS server by just pasting the content of config/opendkim/keys/domain.tld/mail.txt in your domain.tld.hosts zone.

⁠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:

$ pwd
/where/docker-mailserver/resides/

$ ls -lhA
-rw-r--r-- USER GROUP SIZE DATE .env
-rw-r--r-- USER GROUP SIZE DATE docker-compose.yml
-rw-r--r-- USER GROUP SIZE DATE mailserver.env

# 1. Either create the config/ directory yourself
#    or let docker-mailserver create it on initial
#    startup
$ mkdir config
$ cd config

# 2. Create the user-patches.sh script and make it
#    executable
$ touch user-patches.sh
$ chmod +x user-patches.sh
$ ls -lh
-rwxr-xr-x USER GROUP SIZE DATE user-patches.sh

# 3. Edit it
$ vi user-patches.sh
$ cat user-patches.sh
#! /bin/bash

# ! THIS IS AN EXAMPLE !

# If you modify any supervisord configuration, make sure
# to run "supervisorctl update" afterwards.

set -euo pipefail
echo 'user-patches.sh started'

if ! grep '192.168.0.1' /etc/hosts
then
  echo -e '192.168.0.1 some.domain.com' >> /etc/hosts
fi

sed -i "s/smtpd_sender_restrictions = /smtpd_sender_restrictions = reject_unknown_reverse_client_hostname, /" /etc/postfix/main.cf
sed -i "s/smtpd_sender_restrictions = /smtpd_sender_restrictions = reject_unknown_client_hostname, /" /etc/postfix/main.cf

echo 'user-patches.sh finished successfully'

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:

./setup.sh email add [email protected]
./setup.sh email add [email protected]
./setup.sh email add [email protected]

⁠Updating docker-mailserver

docker-compose down
docker pull tvial/docker-mailserver:<VERSION TAG>
docker-compose up -d mail

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 a try. You enable SRS by setting ENABLE_SRS=1. See the variable description for further information.

⁠Exposed ports

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 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. Originally a secure variant of port 25.

See the 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.

version: '3.8'

services:
  mail:
    image: docker.io/tvial/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

version: '3.8'

services:
  mail:
    image: docker.io/tvial/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))
      - [email protected]
      - POSTFIX_MESSAGE_SIZE_LIMIT=100000000
    cap_add:
      - NET_ADMIN
      - SYS_PTRACE
    restart: always

volumes:
  maildata:
  mailstate:
  maillogs:

⁠Environment Variables

If an option doesn't work as documented here, check if you are running the latest image! Values in bold are the default values.

Note: Since docker-mailserver v7.1.0, comparisons for environment variables are executed differently. If you previously used VARIABLE='' as the empty value, please update to now use VARIABLE=.

⁠Assignments

⁠General

⁠DMS_DEBUG

• 0 => Debug disabled
• 1 => Enables debug on startup

⁠ENABLE_CLAMAV

• 0 => Clamav is disabled
• 1 => Clamav is enabled

⁠ONE_DIR

• 0 => state in default directories
• 1 => consolidate all states into a single directory (/var/mail-state) to allow persistence using docker volumes

⁠ENABLE_POP3

• empty => POP3 service disabled
• 1 => Enables POP3 service

⁠ENABLE_FAIL2BAN

• 0 => fail2ban service disabled
• 1 => Enables fail2ban service

If you enable Fail2Ban, don't forget to add the following lines to your docker-compose.yml:

cap_add:
  - NET_ADMIN

Otherwise, iptables won't be able to ban IPs.

⁠SMTP_ONLY

• empty => all daemons start
• 1 => only launch postfix smtp

⁠SSL_TYPE

• empty => SSL disabled
• letsencrypt => Enables Let's Encrypt certificates
• custom => Enables custom certificates
• manual => Let you manually specify locations of your SSL certificates for non-standard cases
  • self-signed => Enables self-signed certificates
  • any other value => SSL required, settings by default

Please read the SSL page in the wiki⁠ for more information.

⁠TLS_LEVEL

• empty => modern
• modern => Enables TLSv1.2 and modern ciphers only. (default)
• intermediate => Enables TLSv1, TLSv1.1 and TLSv1.2 and broad compatibility ciphers.
• old => NOT implemented. If you really need it, then customize the TLS ciphers overriding postfix and dovecot settings wiki⁠

⁠SPOOF_PROTECTION

Configures the handling of creating mails with forged sender addresses.

• empty => Mail address spoofing allowed. Any logged in user may create email messages with a forged sender address. See also Wikipedia⁠(not recommended, but default for backwards compatibility reasons)
• 1 => (recommended) Mail spoofing denied. Each user may only send with his own or his alias addresses. Addresses with extension delimiters⁠ are not able to send messages.

⁠ENABLE_SRS

Enables the Sender Rewriting Scheme. SRS is needed if your mail server acts as forwarder. See postsrsd⁠ for further explanation.

• 0 => Disabled
• 1 => Enabled

⁠PERMIT_DOCKER

Set different options for mynetworks option (can be overwrite in postfix-main.cf) WARNING: Adding the docker network's gateway to the list of trusted hosts, e.g. using the network or connected-networks option, can create an open relay⁠, for instance⁠ if IPv6 is enabled on the host machine but not in Docker.

• empty => localhost only
• host => Add docker host (ipv4 only)
• network => Add the docker default bridge network (172.16.0.0/12); WARNING: docker-compose might use others (e.g. 192.168.0.0/16) use PERMIT_DOCKER=connected-networks in this case
• connected-networks => Add all connected docker networks (ipv4 only)

Note: you probably want to set POSTFIX_INET_PROTOCOLS=ipv4⁠ to make it work fine with Docker.

⁠NETWORK_INTERFACE

In case your network interface differs from eth0, e.g. when you are using HostNetworking in Kubernetes, you can set this to whatever interface you want. This interface will then be used.

• empty => eth0

⁠VIRUSMAILS_DELETE_DELAY

Set how many days a virusmail will stay on the server before being deleted

• empty => 7 days

⁠ENABLE_POSTFIX_VIRTUAL_TRANSPORT

This Option is activating the Usage of POSTFIX_DAGENT to specify a ltmp client different from default dovecot socket.

• empty => disabled
• 1 => enabled

⁠POSTFIX_DAGENT

Enabled by ENABLE_POSTFIX_VIRTUAL_TRANSPORT. Specify the final delivery of postfix

• empty: fail
• lmtp:unix:private/dovecot-lmtp (use socket)
• lmtps:inet:<host>:<port> (secure lmtp with starttls, take a look at https://sys4.de/en/blog/2014/11/17/sicheres-lmtp-mit-starttls-in-dovecot/⁠)
• lmtp:<kopano-host>:2003 (use kopano as mailstore)
• etc.

⁠POSTFIX_MAILBOX_SIZE_LIMIT

Set the mailbox size limit for all users. If set to zero, the size will be unlimited (default).

• empty => 0 (no limit)

⁠ENABLE_QUOTAS

• 1 => Dovecot quota is enabled
• 0 => Dovecot quota is disabled

See mailbox quota⁠.

⁠POSTFIX_MESSAGE_SIZE_LIMIT

Set the message size limit for all users. If set to zero, the size will be unlimited (not recommended!)

• empty => 10240000 (~10 MB)

⁠ENABLE_MANAGESIEVE

• empty => Managesieve service disabled
• 1 => Enables Managesieve on port 4190

⁠OVERRIDE_HOSTNAME

• empty => uses the hostname command to get the mail server's canonical hostname
• => Specify a fully-qualified domainname to serve mail for. This is used for many of the config features so if you can't set your hostname (e.g. you're in a container platform that doesn't let you) specify it in this environment variable.

⁠POSTMASTER_ADDRESS

• empty => [email protected]⁠
• => Specify the postmaster address

⁠POSTSCREEN_ACTION

• enforce => Allow other tests to complete. Reject attempts to deliver mail with a 550 SMTP reply, and log the helo/sender/recipient information. Repeat this test the next time the client connects.
• drop => Drop the connection immediately with a 521 SMTP reply. Repeat this test the next time the client connects.
• ignore => Ignore the failure of this test. Allow other tests to complete. Repeat this test the next time the client connects. This option is useful for testing and collecting statistics without blocking mail.

⁠DOVECOT_MAILBOX_FORMAT

• maildir => uses very common Maildir format, one file contains one message
• sdbox => (experimental) uses Dovecot high-performance mailbox format, one file contains one message
• mdbox ==> (experimental) uses Dovecot high-performance mailbox format, multiple messages per file and multiple files per box

This option has been added in November 2019. Using other format than Maildir is considered as experimental in docker-mailserver and should only be used for testing purpose. For more details, please refer to Dovecot Documentation⁠.

⁠POSTFIX_INET_PROTOCOLS

• all => All possible protocols.
• ipv4 => Use only IPv4 traffic. Most likely you want this behind Docker.
• ipv6 => Use only IPv6 traffic.

Note: More details in http://www.postfix.org/postconf.5.html#inet_protocols⁠

⁠Reports

⁠PFLOGSUMM_TRIGGER

Enables regular pflogsumm mail reports.

• not set => No report
• daily_cron => Daily report for the previous day
• logrotate => Full report based on the mail log when it is rotated

This is a new option. The old REPORT options are still supported for backwards compatibility. If this is not set and reports are enabled with the old options, logrotate will be used.

⁠PFLOGSUMM_RECIPIENT

Recipient address for pflogsumm reports.

• not set => Use REPORT_RECIPIENT or POSTMASTER_ADDRESS
• => Specify the recipient address(es)

⁠PFLOGSUMM_SENDER

From address for pflogsumm reports.

• not set => Use REPORT_SENDER or POSTMASTER_ADDRESS
• => Specify the sender address

⁠LOGWATCH_INTERVAL

Interval for logwatch report.

• none => No report is generated
• daily => Send a daily report
• weekly => Send a report every week

⁠LOGWATCH_RECIPIENT

Recipient address for logwatch reports if they are enabled.

• not set => Use REPORT_RECIPIENT or POSTMASTER_ADDRESS
• => Specify the recipient address(es)

⁠REPORT_RECIPIENT (deprecated)

Enables a report being sent (created by pflogsumm) on a regular basis.

• 0 => Report emails are disabled unless enabled by other options
• 1 => Using POSTMASTER_ADDRESS as the recipient
• => Specify the recipient address

⁠REPORT_SENDER (deprecated)

Change the sending address for mail report

• empty => mailserver-report@hostname
• => Specify the report sender (From) address

⁠REPORT_INTERVAL (deprecated)

Changes the interval in which logs are rotated and a report is being sent (deprecated).

• daily => Send a daily report
• weekly => Send a report every week
• monthly => Send a report every month

Note: This variable used to control logrotate inside the container and sent the pflogsumm report when the logs were rotated. It is still supported for backwards compatibility, but the new option LOGROTATE_INTERVAL has been added that only rotates the logs.

⁠LOGROTATE_INTERVAL

Defines the interval in which the mail log is being rotated.

• daily => Rotate daily.
• weekly => Rotate weekly.
• monthly => Rotate monthly.

Note that only the log inside the container is affected. The full log output is still available via docker logs mail (or your respective container name). If you want to control logrotation for the docker generated logfile see: Docker Logging Drivers⁠.

Also note that by default the logs are lost when the container is recycled. To keep the logs, mount a volume.

Finally the logrotate interval may affect the period for generated reports. That is the case when the reports are triggered by log rotation.

⁠Spamassassin

⁠ENABLE_SPAMASSASSIN

• 0 => Spamassassin is disabled
• 1 => Spamassassin is enabled

/!\ Spam delivery: when Spamassassin is enabled, messages marked as spam WILL NOT BE DELIVERED. Use SPAMASSASSIN_SPAM_TO_INBOX=1 for receiving spam messages.

⁠SPAMASSASSIN_SPAM_TO_INBOX

• 0 => Spam messages will be bounced (rejected) without any notification (dangerous).
• 1 => Spam messages will be delivered to the inbox and tagged as spam using SA_SPAM_SUBJECT.

⁠MOVE_SPAM_TO_JUNK

• 1 => Spam messages will be delivered in the Junk folder.
• 0 => Spam messages will be delivered in the mailbox.

Note: this setting needs SPAMASSASSIN_SPAM_TO_INBOX=1

⁠SA_TAG

• 2.0 => add spam info headers if at, or above that level

Note: this spamassassin setting needs ENABLE_SPAMASSASSIN=1

⁠SA_TAG2

• 6.31 => add 'spam detected' headers at that level

Note: this spamassassin setting needs `ENABLE