[TODO]: Refactor parallel feature support for Fetchmail / Getmail #4713

services:
  dms-local:
    image: ghcr.io/docker-mailserver/docker-mailserver:15.1
    hostname: mail.example.test
    environment:
      ENABLE_FETCHMAIL: 1
      # This setting splits the fetchmail config by `poll` lines,
      # each with their own supervisord service created.
      FETCHMAIL_PARALLEL: 1
      # Lowered polling from default 300s for quick testing feedback:
      # NOTE: Polling is irrelevant for any configs using `idle`.
      FETCHMAIL_POLL: 10
      # Only required if the sender address used at the remote cannot resolve:
      # This is because fetchmail is attempting to deliver the mail through standard
      # SMTP, however Postfix security checks are still applied (without this workaround).
      PERMIT_DOCKER: container
    configs:
      - source: dms-accounts
        target: /tmp/docker-mailserver/postfix-accounts.cf
      - source: fetchmail
        target: /tmp/docker-mailserver/fetchmail.cf

  # This would represent an external mail service like Gmail:
  dms-remote:
    image: ghcr.io/docker-mailserver/docker-mailserver:15.1
    hostname: mail.remote.test
    environment:
      # Allows for us send a test mail easily by trusting any mail client run within this container (`swaks`):
      PERMIT_DOCKER: container
      # Required to enable (if testing spam delivery to/from the `Junk` mailbox).
      # `dms-local` will pull mail from Alice's junk mail and then store a copy
      # into John's junk mailbox (due to default sieve scripts paired with headers added by SpamAssassin).
      ENABLE_SPAMASSASSIN: 1
    configs:
      - source: dms-accounts-remote
        target: /tmp/docker-mailserver/postfix-accounts.cf
      # This file is copied over to `/var/mail/remote.test/alice/home/.dovecot.sieve` during container setup:
      - source: sieve
        target: /tmp/docker-mailserver/alice@remote.test.dovecot.sieve


# Using the Docker Compose `configs.content` feature instead of volume mounting separate files.
# NOTE: This feature requires Docker Compose v2.23.1 (Nov 2023) or newer:
# https://github.com/compose-spec/compose-spec/pull/446
configs:
  # Fetchmail config docs:
  # https://www.fetchmail.info/fetchmail-man.html
  # https://docker-mailserver.github.io/docker-mailserver/v15.1/config/advanced/mail-fetchmail/
  #
  # Config to remotely monitor the two accounts and copy remote mail into the local `john.doe` mailbox.
  # NOTE: `no sslcertck` used as this compose example has no TLS certs configured for DMS.
  #
  # Default delivery is via SMTP (via default: `smtphost localhost/25`_) to the `is` recipient address.
  # Alternatives require either unix socket write access (LMTP) or execute permissions (CLI),
  # these would require modifications in DMS or running Fetchmail as root.
  # Consult upstream docs before deciding to pursue either alternative:
  # - LMTP protocol (skip Postfix, direct to Dovecot): `smtphost /var/run/dovecot/lmtp`
  # - MDA/LDA command (CLI submission to Dovecot): `mda "/usr/lib/dovecot/deliver -d %T"`
  # Another option would be SMTP (Postfix) with trust established to relax security,
  # be mindful of Anti-(virus/spam) or similar integrations impact on delivery.
  fetchmail:
    content: |
      poll 'mail.remote.test' proto imap
        user 'jane.doe@remote.test' pass 'secret'
        is 'john.doe@example.test'
        idle
        no sslcertck

      # The `folders` setting (default: INBOX) can monitor multiple remote mailboxes:
      # This is necessary if other mailboxes of interest exist at the remote.
      # NOTE: Mailbox hierarchy does not result in recursively pulling from child mailboxes,
      #       they must be explicitly configured instead.
      # NOTE: When using `idle`, the `folders` setting must only specify at most 1 mailbox,
      #       otherwise the fetchmail command will fail to start (validation failure).
      poll 'mail.remote.test' proto imap
        user 'alice@remote.test' pass 'secret'
        folders 'INBOX', 'Junk', 'INBOX.nested-mailbox'
        is 'john.doe@example.test'
        no sslcertck

  # When the subaddress `+sieve-example` is used, store mail in a mailbox (folder) nested under `INBOX` mailbox:
  sieve:
    content: |
      require ["envelope", "fileinto", "mailbox", "subaddress", "variables"];

      # Check if the mail recipient address uses the expected subaddress tag (sourced from `:detail`)
      if envelope :detail :matches "to" "sieve-example" {

        if mailboxexists "INBOX.nested-mailbox" {
          fileinto "INBOX.nested-mailbox";
        } else {
          fileinto :create "INBOX.nested-mailbox";
        }
      }

  # DMS requires an account to complete setup, configure at least one account for each DMS container:
  # NOTE: All accounts are configured with the same example password (`secret`, SHA512-CRYPT hashed)
  # NOTE: `$$` is an escaped `$` (opt-out of pre-processing for environment variable interpolation)
  dms-accounts:
    content: |
      john.doe@example.test|{SHA512-CRYPT}$$6$$sbgFRCmQ.KWS5ryb$$EsWrlYosiadgdUOxCBHY0DQ3qFbeudDhNMqHs6jZt.8gmxUwiLVy738knqkHD4zj4amkb296HFqQ3yDq4UXt8.

  dms-accounts-remote:
    content: |
      jane.doe@remote.test|{SHA512-CRYPT}$$6$$sbgFRCmQ.KWS5ryb$$EsWrlYosiadgdUOxCBHY0DQ3qFbeudDhNMqHs6jZt.8gmxUwiLVy738knqkHD4zj4amkb296HFqQ3yDq4UXt8.
      alice@remote.test|{SHA512-CRYPT}$$6$$sbgFRCmQ.KWS5ryb$$EsWrlYosiadgdUOxCBHY0DQ3qFbeudDhNMqHs6jZt.8gmxUwiLVy738knqkHD4zj4amkb296HFqQ3yDq4UXt8.