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.

Includes:

• postfix with smtp or ldap auth
• dovecot for sasl, imap (and optional pop3) with ssl support, with ldap auth
• saslauthd with ldap auth
• amavis
• spamassasin supporting custom rules
• clamav with automatic updates
• opendkim
• opendmarc
• fail2ban
• fetchmail
• postgrey
• basic sieve support using dovecot
• LetsEncrypt and self-signed certificates
• persistent data and state (but think about backups!)
• integration tests
• automated builds on docker hub

Why I created this image: Simple mail server with Docker

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

docker pull tvial/docker-mailserver:latest

Adapt this file with your FQDN. Install docker-compose in the version 1.6 or higher.

Your configs must be mounted in /tmp/docker-mailserver/. To understand how things work on boot, please have a look to start-mailserver.sh

restart: always ensures that the mail server container (and ELK container when using the mail server together with ELK stack) is automatically restarted by Docker in cases like a Docker service or host restart or container exit.

version: '2'

services:
  mail:
    image: tvial/docker-mailserver:2.1
    hostname: mail
    domainname: domain.com
    container_name: mail
    ports:
    - "25:25"
    - "143:143"
    - "587:587"
    - "993:993"
    volumes:
    - maildata:/var/mail
    - mailstate:/var/mail-state
    - ./config/:/tmp/docker-mailserver/
    environment:
    - ENABLE_SPAMASSASSIN=1
    - ENABLE_CLAMAV=1
    - ENABLE_FAIL2BAN=1
    - ENABLE_POSTGREY=1
    - ONE_DIR=1
    - DMS_DEBUG=0
    cap_add:
    - NET_ADMIN

volumes:
  maildata:
    driver: local
  mailstate:
    driver: local

Don't forget to adapt MAIL_USER and MAIL_PASS to your needs

mkdir -p config
touch config/postfix-accounts.cf
docker run --rm \
  -e [email protected] \
  -e MAIL_PASS=mypassword \
  -ti tvial/docker-mailserver:latest \
  /bin/sh -c 'echo "$MAIL_USER|$(doveadm pw -s SHA512-CRYPT -u $MAIL_USER -p $MAIL_PASS)"' >> config/postfix-accounts.cf

docker run --rm \
  -v "$(pwd)/config":/tmp/docker-mailserver \
  -ti tvial/docker-mailserver:latest generate-dkim-config

Now 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.

Note: you can also manage email accounts, DKIM keys and more with the setup.sh convenience script.

docker-compose up -d mail

You're done!

Please check how the container starts to understand what's expected. Also if an option doesn't work as documented here, check if you are running the latest image!

Value in bold is the default value.

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

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

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

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

Note: this spamassassin setting needs ENABLE_SPAMASSASSIN=1

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

Note: this spamassassin setting needs ENABLE_SPAMASSASSIN=1

• 6.31 => triggers spam evasive actions

Note: this spamassassin setting needs ENABLE_SPAMASSASSIN=1

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

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

• 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.

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

• 0 => fetchmail disabled
• 1 => fetchmail enabled

• empty => LDAP authentification is disabled
• 1 => LDAP authentification is enabled
• NOTE:
  • A second container for the ldap service is necessary (e.g. docker-openldap)
  • For preparing the ldap server to use in combination with this continer this article may be helpful

• empty => mail.domain.com
• => Specify the dns-name/ip-address where the ldap-server
• NOTE: If you going to use the mailserver in combination with docker-compose you can set the service name here

• empty => ou=people,dc=domain,dc=com
• => e.g. LDAP_SEARCH_BASE=dc=mydomain,dc=local

• empty => cn=admin,dc=domain,dc=com
• => take a look at examples of SASL_LDAP_BIND_DN

• empty => admin
• => Specify the password to bind against ldap

• 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.

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

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

• 300 => greylist for N seconds

Note: This postgrey setting needs ENABLE_POSTGREY=1

• 35 => delete entries older than N days since the last time that they have been seen

Note: This postgrey setting needs ENABLE_POSTGREY=1

• Delayed by postgrey => response when a mail is greylisted

Note: This postgrey setting needs ENABLE_POSTGREY=1

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

• empty => pam
• ldap => authenticate against ldap server
• shadow => authenticate against local user db
• mysql => authenticate against mysql db
• rimap => authenticate against imap server
• NOTE: can be a list of mechanisms like pam ldap shadow

• empty => None
• e.g. with SASLAUTHD_MECHANISMS rimap you need to specify the ip-address/servername of the imap server ==> xxx.xxx.xxx.xxx

• empty => localhost

• empty or 0 => ldap:https:// will be used
• 1 => ldaps:https:// will be used

• empty => anonymous bind
• specify an object with priviliges to search the directory tree
• e.g. active directory: SASLAUTHD_LDAP_BIND_DN=cn=Administrator,cn=Users,dc=mydomain,dc=net
• e.g. openldap: SASLAUTHD_LDAP_BIND_DN=cn=admin,dc=mydomain,dc=net

• empty => anonymous bind

• empty => Reverting to SASLAUTHD_MECHANISMS pam
• specify the search base

• empty => default filter (&(uniqueIdentifier=%u)(mailEnabled=TRUE))
• e.g. for active directory: (&(sAMAccountName=%U)(objectClass=person))
• e.g. for openldap: (&(uid=%U)(objectClass=person))

• empty => No sasl_passwd will be created
• string => /etc/postfix/sasl_passwd will be created with the string as password

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

• empty => SSL disabled
• letsencrypt => Enables Let's Encrypt certificates
• custom => Enables custom certificates
• manual => Let's you manually specify locations of your SSL certificates for non-standard cases
• self-signed => Enables self-signed certificates

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

Set different options for mynetworks option (can be overwrite in postfix-main.cf)

• empty => localhost only
• host => Add docker host (ipv4 only)
• network => Add all docker containers (ipv4 only)

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

• empty => 7 days

This Option is activating the Usage of POSTFIX_DAGENT to specify a ltmp client different from default dovecot socket. - empty => disabled - 1 => enabled

Enabled by ENABLE_POSTFIX_VIRTUAL_TRANSPORT. Specify the final delivery of postfix - empty: fail - lmtp:unix:private/dovecot-lmtp (use socket) - lmtps:inet:: (secure lmtp with starttls, take a look at https://sys4.de/en/blog/2014/11/17/sicheres-lmtp-mit-starttls-in-dovecot/) - lmtp::2003 (use kopano as mailstore) - etc.