petronem/mailserver repository overview

⁠hardware/mailserver

⁠Build

⁠Docker image

Simple and full-featured mail server as a set of multiple docker images includes :

• Postfix : a full set smtp email server supporting custom rules
• Dovecot : secure imap and pop3 email server
• Amavis : content filter implementing decoding, processing and checking e-mails
• Spamassasin : anti-spam filter
• Clamav : antivirus with automatic updates
• OpenDKIM : implementation of DKIM (Domain Keys Identified Mail)
• OpenDMARC : implementation of DMARC (Domain-based Message Authentication, Reporting & Conformance)
• Sieve : email filtering (vacation auto-responder, auto-forward...etc)
• Fetchmail : fetch e-mails from external IMAP/POP3 server into local mailbox
• Postgrey : greylisting policy server
• Gross : greylisting of suspicious sources
• Rainloop : web based email client
• Postfixadmin : web based administration interface
• NSD : authoritative DNS server with DNSSEC support
• Nginx : web server with HTTP/2 and TLS 1.3 (DRAFT), statically linked against BoringSSL
• SSL : lets encrypt and self-signed certificates support
• Supporting multiple virtual domains over MySQL backend
• Integration tests with Travis CI
• Automated builds on DockerHub

⁠How to use

⁠1 - Get latest image

# Pull from hub.docker.com :
docker pull hardware/mailserver

# or build it manually :
docker build -t hardware/mailserver https://github.com/hardware/mailserver.git#master

⁠2 - Get latest docker-compose.yml

See docker-compose.sample.yml⁠

Note : Change your hostname / domain name, and adapt to your needs

⁠3 - Reverse proxy setup

See Reverse proxy configuration⁠

Start the mailstack :

docker-compose up -d

⁠4 - Control panel setup / virtual domains and mailboxes creation

See Postfixadmin initial configuration⁠

⁠5 - Webmail setup (optional)

See Rainloop initial configuration⁠

⁠6 - DNS records

HOSTNAME            CLASS             RECORD TYPE          VALUE
------------------------------------------------------------------------------------------------
mail                IN                A                    SERVER_IPV4
@                   IN                MX          10       mail.domain.tld.
@                   IN                TXT                  "v=spf1 a mx ip4:SERVER_IPV4 ~all"
mail._domainkey     IN                TXT                  "v=DKIM1; k=rsa; p=DKIM Public Key"
_dmarc              IN                TXT                  "v=DMARC1; p=reject; rua=mailto:[email protected]; ruf=mailto:[email protected]; fo=0; adkim=s; aspf=s; pct=100; rf=afrf; sp=reject"

The DKIM public key is available on host here : /mnt/docker/mail/opendkim/domain.tld/mail.txt

See NSD initial configuration⁠, if you want to setup your own authoritative dns server with dnssec support :lock:

You can audit your mailserver with the following assessment services :

• https://www.mail-tester.com/⁠
• https://observatory.mozilla.org/⁠
• https://www.hardenize.com/⁠

⁠7 - Done, congratulation ! :tada:

At first launch, the container takes few minutes to generate SSL certificates (if needed), Diffie-Hellman parameters, DKIM keypair and update clamav database, all of this takes some time, be patient...

You can check startup logs with this command :

docker logs -f mailserver

⁠Environment variables

If DISABLE_CLAMAV and DISABLE_SPAMASSASSIN are both set to true, Amavis is also completely disabled.

The supported values for GREYLISTING are off, gross or postgrey. Gross is a more advanced greylisting server which blocks only hosts with a bad DNSBL reputation.

Currently, only a single RECIPIENT_DELIMITER is supported. Support for multiple delimiters will arrive with Dovecot v2.3.

FETCHMAIL_INTERVAL must be a number between 1 and 59 minutes.

### Files/Folders tree

/mnt/docker
└──mail
   ├──postfix
   │     custom.conf
   ├──postgrey
   │     postgrey.db
   │     ...
   ├──gross
   │     grossd.state
   ├──sieve
   │     default.sieve
   │     default.svbin
   ├──opendkim
   │  ├──domain.tld
   │  │     mail.private
   │  │     mail.txt
   ├──ssl
   │  ├──dhparams
   │  │     dh512.pem
   │  │     dh2048.pem
   │  ├──live (Let's Encrypt or other CA)
   │  │  ├──mail.domain.tld
   │  │  │     privkey.pem
   │  │  │     cert.pem
   │  │  │     chain.pem
   │  │  │     fullchain.pem
   │  ├──selfsigned (Auto-generated if no certificate found)
   │  │     cert.pem
   │  │     privkey.pem
   ├──vhosts
   │  ├──domain.tld
   │  │  ├──user
   │  │  │     .dovecot.sieve -> sieve/rainloop.user.sieve
   │  │  │     .dovecot.svbin
   │  │  │  ├──mail
   │  │  │  │  ├──.Archive
   │  │  │  │  ├──.Drafts
   │  │  │  │  ├──.Sent
   │  │  │  │  ├──.Spam
   │  │  │  │  ├──.Trash
   │  │  │  │  ├──cur
   │  │  │  │  ├──new
   │  │  │  │     ...
   │  │  │  ├──sieve
   │  │  │  │     rainloop.user.sieve (if using rainloop webmail)

⁠Let's Encrypt certificate authority

To use Let's Encrypt certificates, setup your docker-compose.yml file like this :

mailserver:
  image: hardware/mailserver
  volumes:
    - /mnt/docker/nginx/certs:/etc/letsencrypt
    ...

nginx:
  image: wonderfall/boring-nginx
  volumes:
    - /mnt/docker/nginx/certs:/certs
    ...

Then generate Let's Encrypt certificates with xataz/letsencrypt⁠, you can use other tools like lego⁠ if you want.

docker-compose stop nginx

docker run -it --rm \
  -v /mnt/docker/nginx/certs:/etc/letsencrypt \
  -p 80:80 -p 443:443 \
  xataz/letsencrypt \
    certonly --standalone \
    --rsa-key-size 4096 \
    --agree-tos \
    -m [email protected] \
    -d mail.domain.tld \ # <--- Mail FQDN is the first domain name, very important !
    -d webmail.domain.tld \
    -d postfixadmin.domain.tld

docker-compose up -d

• :warning: The common name of your ssl certifcate MUST be the same as your server's FQDN (for exemple, let's encrypt live subfolder name must be egual to domainname & hostname values of docker-compose file). Don't forget to add your FQDN in command above in first position.

• If you do not use let's encrypt, a default self-signed certificate (RSA 4096 bits SHA2) is generated here : /mnt/docker/mail/ssl/selfsigned/{cert.pem, privkey.pem}.

⁠Another certificate authority (other than Let's Encrypt)

Put your certificates in /mnt/docker/nginx/certs/live/mail.domain.tld

:warning: Required files in this folder :

• privkey.pem : Private key for the certificate
• cert.pem : Server certificate only
• chain.pem : Root and intermediate certificates only, excluding server certificate
• fullchain.pem : All certificates, including server certificate. This is concatenation of cert.pem and chain.pem

Then mount the volume like this :

mailserver:
  image: hardware/mailserver
  volumes:
    - /mnt/docker/nginx/certs:/etc/letsencrypt
    ...

⁠Override postfix configuration

Postfix default configuration can be overrided providing a custom configuration file at postfix format. This can be used to also add configuration that are not in default configuration. Postfix documentation⁠ remains the best place to find configuration options.

Each line in the provided file will be loaded into Postfix. Create a new file here /mnt/docker/mail/postfix/custom.conf and add your custom options inside.

Example :

# /mnt/docker/mail/postfix/custom.conf

smtpd_banner = $myhostname ESMTP MyGreatMailServer
inet_protocols = ipv4
delay_notice_recipient = [email protected]
delay_warning_time = 2h

docker logs -f mailserver

[INFO] Override : smtpd_banner = $myhostname ESMTP MyGreatMailServer
[INFO] Override : inet_protocols = ipv4
[INFO] Override : delay_notice_recipient = [email protected]
[INFO] Override : delay_warning_time = 2h
[INFO] Custom Postfix configuration file loaded

⁠Email client settings :

• IMAP/SMTP username : [email protected]⁠
• Incoming IMAP server : mail.domain.tld (your FQDN)
• Outgoing SMTP server : mail.domain.tld (your FQDN)
• IMAP port : 993
• SMTP port : 587
• IMAP Encryption protocol : SSL/TLS
• SMTP Encryption protocol : STARTTLS

⁠Components

• Postfix 2.11.3
• Dovecot 2.2.13
• OpenDKIM 2.9.2
• OpenDMARC 1.3.0
• Spamassassin 3.4.0
• Postgrey 1.35
• Fetchmail 6.3.26
• ClamAV 0.98.7
• Amavisd-new 2.10.1
• Amavisd-milter 1.5.0
• Supervisor 3.0r1
• Rsyslog 8.4.2
• ManageSieve server

⁠Roadmap

• Use Rspamd instead of Spamassassin
• ClueGetter integration
• LDAP authentification (need contributors)

⁠How to contribute

• Fork this repository
• Create a new feature branch for a new functionality or bugfix
• Code...
• Add integration tests in test/tests.bats
• Use make to build image locally and run tests
• Document your improvements
• Commit your changes
• Push your code and open a new pull request
• Use issues⁠ for any questions