Minimalistic Docker Mail Box (smtp + imap) Postfix/Dovecot (ghcr.io/servercontainers/minimail) [x86 + arm]

maintained by ServerContainers

What is it

This Dockerfile (available as self build container) gives you a dovecot and postfix installation is meant to store mails, handle authentication and users and a new version (completely rewritten) of ServerContainers/mail-box.

What makes it better?

• Alpine Linux Base (smaller footprint)
• Configure Users and Emails using Environment Variables
• Internaly only plain textfiles (texthash) are used (passdb, virtual stuff etc.)
• Just 3 Daemons - runit and postfix + dovecot
• Blowfish Crypt Password Hashing (bcrypt) available (doveadm pw -s BLF-CRYPT or docker run --rm -ti alpine sh -c 'apk add dovecot; doveadm pw -s BLF-CRYPT')

It's based on the _/alpine Image (3.12)

View in GitHub Registry ghcr.io/servercontainers/minimail

View in GitHub ServerContainers/minimail

currently tested on: x86_64, arm64, arm

IMPORTANT!

In March 2023 - Docker informed me that they are going to remove my organizations servercontainers and desktopcontainers unless I'm upgrading to a pro plan.

I'm not going to do that. It's more of a professionally done hobby then a professional job I'm earning money with.

In order to avoid bad actors taking over my org. names and publishing potenial backdoored containers, I'd recommend to switch over to my new github registry: ghcr.io/servercontainers.

Build & Versions

You can specify DOCKER_REGISTRY environment variable (for example my.registry.tld) and use the build script to build the main container and it's variants for x86_64, arm64 and arm

You'll find all images tagged like a3.15.0-p3.6.3-r1-d2.3.17.1-r0 which means a<alpine version>-p<postfix version>-d<dovecot version>. This way you can pin your installation/configuration to a certian version. or easily roll back if you experience any problems (don't forget to open a issue in that case ;D).

To build a latest tag run ./build.sh release

Changelogs

• 2024-09-22
  • updated settings
  • updated tls settings
  • added pre generated dh4096.pem dh parameter file to speed up build time
• 2023-03-20
  • github action to build container
  • implemented ghcr.io as new registry
• 2023-03-17
  • switched from docker hub to a build-yourself container
• 2022-01-08
  • better build script
• 2021-12-31
  • new build process and version pinning
• 2021-07-28
  • healthcheck will fail if certificate is 3 days or less valid or already expired
• 2021-06-04
  • added healthcheck (will fail when certs are updated without container restart)
• 2021-05-25
  • removed tls session cache
• 2021-03-21
  • update and missing hash: support fix -> now texthash without postmap

Environment variables

OFFICIAL DATABASE MANAGMENT ENVIRONMENT VARIABLES

this on is needed to create a user/email, add a password hash to it and configure it's aliases

• ACONF_USER_ACCOUNT_NAME_[...]

  • [...] must be replaced with an id to connect all the envs for one account together
  • the email address is specified in the value. e.g.: test@mail.tld

• ACONF_USER_PASSWORD_HASH_[...]

  • [...] must be replaced with an id to connect all the envs for one account together
  • the password hash is specified in the value. e.g.: {BLF-CRYPT}$2y$05$4KFe0ntflWQ...
  • Note: for a docker compose file you need to replace each $ with a $$ (then it's escaped and works)

• ACONF_USER_ALIASES_[...]

  • [...] must be replaced with an id to connect all the envs for one account together
  • the aliases for this users email are specified (use a blank to seperate multiplte) in the value. e.g.: postmaster@mail.tld admin@mail.tld info@mail.tld

the main postmaster address will be the first address containing postmaster or the first address specified

OFFICIAL MAIL ENVIRONMENT VARIABLES

• MAIL_FQDN

  • specify the mailserver name - only add FQDN not a hostname!
  • e.g. my.mailserver.example.com

• POSTFIX_SMTPD_BANNER

  • alter the SMTPD Banner of postfix e.g. mailserver.example.local ESMTP

• POSTFIX_MYDESTINATION

  • specify the domains which this mail-box handles

• AUTO_TRUST_NETWORKS

  • add all networks this container is connected to and trust them to send mails
  • set to any value to enable

• ADDITIONAL_MYNETWORKS

  • add this specific network to the automatically trusted onces

• MYNETWORKS

  • ignore all auto configured mynetworks and replace them with this value
  • overwrites networks specified in ADDITIONAL_MYNETWORKS

• RELAYHOST

  • sets postfix relayhost - please take a look at the official documentation
  • The form enclosed with [] eliminates DNS MX lookups. Don't worry if you don't know what that means. Just be sure to specify the [] around the mailhub hostname that your ISP gave to you, otherwise mail may be mis-delivered.

• POSTFIX_SSL_OUT_CERT

  • path to SSL Client certificate (outgoing connections)
  • default: /etc/postfix/tls/client.crt

• POSTFIX_SSL_OUT_KEY

  • path to SSL Client key (outgoing connections)
  • default: /etc/postfix/tls/client.key

• POSTFIX_SSL_OUT_SECURITY_LEVEL

  • SSL security level for outgoing connections
  • default: may

• POSTFIX_SSL_IN_CERT

  • path to SSL Cert/Bundle (incoming connections)
  • default: /etc/postfix/tls/bundle.crt

• POSTFIX_SSL_IN_KEY

  • path to SSL Cert key (incoming connections)
  • default: /etc/postfix/tls/cert.key

• POSTFIX_SSL_IN_SECURITY_LEVEL

  • SSL security level for incoming connections
  • default: may

• POSTFIX_QUEUE_LIFETIME_BOUNCE

  • The maximal time a BOUNCE MESSAGE is queued before it is considered undeliverable
  • By default, this is the same as the queue life time for regular mail

• POSTFIX_QUEUE_LIFETIME_MAX

  • maximum lifetime of regular (non bounce) messages

Volumes

• /etc/postfix/tls
  • this is where the container looks for:
    • dh4096.pem (to overwrite the one generated at container build)
    • rootCA.crt (to check valid client certificates against)
    • client.crt (outgoing SSL Client cert)
    • client.key (outgoing SSL Client key)
    • bundle.crt (incoming SSL Server cert/bundle)
    • cert.key (incoming SSL Server key)
• /etc/postfix/additional
  • this is where the container looks for:
    • transport (postfix transport text-file (texthash) - without been postmaped)
    • header_checks (postfix header_checks regex file)