thy2134/docker-mailserver repository overview

⁠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.

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
• postscreen⁠
• postgrey⁠
• basic sieve support⁠ using dovecot
• LetsEncrypt⁠ and self-signed certificates
• setup script⁠ to easily configure and maintain your mailserver
• 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.

⁠Requirements

Recommended:

• 1 CPU
• 1GB RAM

Minimum:

• 1 CPU
• 512MB RAM

Note: You'll need to deactivate some services like ClamAV to be able to run on a host with 512MB of RAM.

⁠Usage

⁠Get latest image

docker pull tvial/docker-mailserver:latest

⁠Get the tools

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

curl -o setup.sh https://raw.githubusercontent.com/tomav/docker-mailserver/master/setup.sh; chmod a+x ./setup.sh

curl -o docker-compose.yml https://raw.githubusercontent.com/tomav/docker-mailserver/master/docker-compose.yml.dist

curl -o .env https://raw.githubusercontent.com/tomav/docker-mailserver/master/.env.dist

⁠Create a docker-compose environment

• Edit the .env to your liking. Adapt this file with your FQDN.
• Install docker-compose⁠ in the version 1.6 or higher.

⁠Create your mail accounts

./setup.sh email add <user@domain> [<password>]

⁠Generate DKIM keys

./setup.sh config dkim

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.

⁠Start the container

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

⁠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.

⁠For informational purposes:

Your config folder will be mounted in /tmp/docker-mailserver/. To understand how things work on boot, please have a look at 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.

⁠Exposed ports

• 25 receiving email from other mailservers
• 465 SSL Client email submission
• 587 TLS Client email submission
• 143 StartTLS IMAP client
• 993 TLS/SSL IMAP client
• 110 POP3 client
• 995 TLS/SSL POP3 client

Note: Port 25 is only for receiving email from other mailservers and not for submitting email. You need to use port 465 or 587 for this.

⁠Examples with just the relevant environmental variables:

version: '2'

services:
  mail:
    image: tvial/docker-mailserver:latest
    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
    - SYS_PTRACE

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

for ldap setup:

version: '2'

services:
  mail:
    image: tvial/docker-mailserver:latest
    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
      - 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)(mailEnabled=TRUE))"
      - 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
      - [email protected]
    cap_add:
      - NET_ADMIN
      - SYS_PTRACE

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

⁠Environment variables

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.

⁠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'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.

⁠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](https://github.com/tomav/docker-mailserver/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)

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

⁠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.

⁠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.

⁠REPORT_RECIPIENT

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

• 0 => Report emails are disabled
• 1 => Using POSTMASTER_ADDRESS as the recipient
• => Specify the recipient address

⁠REPORT_SENDER

Change the sending address for mail report

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

⁠REPORT_INTERVAL

changes the interval in which a report is being sent.

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

Note: This Variable actually controls logrotate inside the container and rotates the log depending on this setting. The main log output is still available in its entirety via docker logs mail (Or your respective container name). If you want to control logrotation for the docker generated logfile see: Docker Logging Drivers⁠

⁠Spamassassin

⁠ENABLE_SPAMASSASSIN

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

⁠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_SPAMASSASSIN=1

⁠SA_KILL

• 6.31 => triggers spam evasive actions

Note: this spamassassin setting needs ENABLE_SPAMASSASSIN=1

⁠SA_SPAM_SUBJECT

• ***SPAM*** => add tag to subject if spam detected

Note: this spamassassin setting needs ENABLE_SPAMASSASSIN=1

⁠Fetchmail

⁠ENABLE_FETCHMAIL

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

⁠FETCHMAIL_POLL

• 300 => fetchmail The number of seconds for the interval

⁠LDAP

⁠ENABLE_LDAP

• 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

⁠LDAP_START_TLS

• empty => no
• yes => LDAP over TLS enabled for Postfix

⁠LDAP_SERVER_HOST

• 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

⁠LDAP_SEARCH_BASE

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

⁠LDAP_BIND_DN

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

⁠LDAP_BIND_PW

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

⁠LDAP_QUERY_FILTER_USER

• e.g. "(&(mail=%s)(mailEnabled=TRUE))"
• => Specify how ldap should be asked for users

⁠LDAP_QUERY_FILTER_GROUP

• e.g. "(&(mailGroupMember=%s)(mailEnabled=TRUE))"
• => Specify how ldap should be asked for groups

⁠LDAP_QUERY_FILTER_ALIAS

• e.g. "(&(mailAlias=%s)(mailEnabled=TRUE))"
• => Specify how ldap should be asked for aliases

⁠DOVECOT_TLS

• empty => no
• yes => LDAP over TLS enabled for Dovecot

⁠Dovecot

⁠DOVECOT_USER_FILTER

• e.g. "(&(objectClass=PostfixBookMailAccount)(uniqueIdentifier=%n))"

⁠DOVECOT_PASS_FILTER

• e.g. "(&(objectClass=PostfixBookMailAccount)(uniqueIdentifier=%n))"

⁠Postgrey

⁠ENABLE_POSTGREY

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

⁠POSTGREY_DELAY

• 300 => greylist for N seconds

Note: This postgrey setting needs ENABLE_POSTGREY=1

⁠POSTGREY_MAX_AGE

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

Note: This postgrey setting needs ENABLE_POSTGREY=1

⁠POSTGREY_TEXT

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

Note: This postgrey setting needs ENABLE_POSTGREY=1

⁠SASL Auth

⁠ENABLE_SASLAUTHD

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

⁠SASLAUTHD_MECHANISMS

• 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

⁠SASLAUTHD_MECH_OPTIONS

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

⁠SASLAUTHD_LDAP_SERVER

• empty => localhost

⁠SASLAUTHD_LDAP_SSL

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

⁠SASLAUTHD_LDAP_BIND_DN

• 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

⁠SASLAUTHD_LDAP_PASSWORD

• empty => anonymous bind

⁠SASLAUTHD_LDAP_SEARCH_BASE

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

⁠SASLAUTHD_LDAP_FILTER

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

⁠SASL_PASSWD

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

⁠SRS (Sender Rewriting Scheme)

⁠SRS_EXCLUDE_DOMAINS

• empty => Envelope sender will be rewritten for all domains
• provide comma seperated list of domains to exclude from rewriting

⁠SRS_SECRET

• empty => generated when the container is started for the first time
• provide a secret to use in base64
• you may specify multiple keys, comma separated. the first one is used for signing and the remaining will be used for verification. this is how you rotate and expire keys
• if you have a cluster/swarm make sure the same keys are on all nodes
• example command to generate a key: dd if=/dev/urandom bs=24 count=1 2>/dev/null | base64

⁠Multi-domain Relay Hosts

⁠RELAY_HOST

• empty => don't configure relay host
• default host to relay mail through

⁠RELAY_PORT

• empty => 25
• default port to relay mail through

⁠RELAY_USER

• empty => no default
• default relay username (if no specific entry exists in postfix-sasl-password.cf)

⁠RELAY_PASSWORD

• empty => no default
• password for default relay user