diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 000000000..37c3d8664
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,18 @@
+data/
+venv/
+__pycache__
+*.pyc
+*.orig
+*.ini
+.pytest_cache
+.env
+
+# Slim build context — .git/ alone can be 100s of MB
+.git
+.github/
+docs/
+tests/
+
+# Exclude markdown files but keep www/src/*.md (used by WebsiteDeployer)
+*.md
+!www/**/*.md
diff --git a/.github/workflows/test-and-deploy-ipv4only.yaml b/.github/workflows/test-and-deploy-ipv4only.yaml
index 990963eca..c2d4c6857 100644
--- a/.github/workflows/test-and-deploy-ipv4only.yaml
+++ b/.github/workflows/test-and-deploy-ipv4only.yaml
@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - j4n/docker-pr
   pull_request:
     paths-ignore:
       - 'scripts/**'
@@ -11,7 +12,67 @@ on:
       - 'CHANGELOG.md'
       - 'LICENSE'
 
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
 jobs:
+  build-docker:
+    name: Build Docker image
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    outputs:
+      image: ${{ steps.image-ref.outputs.image }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to GHCR
+        if: github.event_name == 'push'
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels)
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            # Tagged releases: v1.2.3 -> :1.2.3, :1.2, :latest
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            # Branch pushes: foo/docker-pr -> :foo-docker-pr
+            type=ref,event=branch
+            # Always: :sha-<hash>
+            type=sha
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: docker/chatmail_relay.dockerfile
+          push: ${{ github.event_name == 'push' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+          build-args: |
+            GIT_HASH=${{ github.sha }}
+
+      - name: Output image reference
+        id: image-ref
+        run: |
+          SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
+          IMAGE="${{ env.REGISTRY }}/$(echo "${{ env.IMAGE_NAME }}" | tr '[:upper:]' '[:lower:]'):sha-${SHORT_SHA}"
+          echo "image=${IMAGE}" >> "$GITHUB_OUTPUT"
+
   deploy:
     name: deploy on staging-ipv4.testrun.org, and run tests
     runs-on: ubuntu-latest
@@ -55,6 +116,7 @@ jobs:
         run: echo venv/bin >>$GITHUB_PATH
 
       - name: upload TLS cert after rebuilding
+        id: wait-for-vps
         run: |
           echo " --- wait until staging-ipv4.testrun.org VPS is rebuilt --- "
           rm ~/.ssh/known_hosts
@@ -68,8 +130,8 @@ jobs:
           rsync -avz dkimkeys-restore/dkimkeys root@staging-ipv4.testrun.org:/etc/ || true
           ssh -o StrictHostKeyChecking=accept-new -v root@staging-ipv4.testrun.org chown root:root -R /var/lib/acme || true
 
-      - name: run deploy-chatmail offline tests 
-        run: pytest --pyargs cmdeploy 
+      - name: run deploy-chatmail offline tests
+        run: pytest --pyargs cmdeploy
 
       - name: setup dependencies
         run: |
@@ -102,3 +164,133 @@ jobs:
       - name: cmdeploy dns
         run: ssh root@staging-ipv4.testrun.org "cd relay && scripts/cmdeploy dns -v --ssh-host localhost"
 
+      # --- Docker deploy (push only, runs even if bare failed) ---
+
+      - name: stop bare services
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          ssh root@staging-ipv4.testrun.org 'systemctl stop postfix dovecot nginx opendkim unbound filtermail doveauth chatmail-metadata iroh-relay mtail fcgiwrap acmetool 2>/dev/null || true'
+
+      - name: install Docker on VPS
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          ssh root@staging-ipv4.testrun.org 'apt-get update && apt-get install -y ca-certificates curl'
+          ssh root@staging-ipv4.testrun.org 'install -m 0755 -d /etc/apt/keyrings'
+          ssh root@staging-ipv4.testrun.org 'curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc && chmod a+r /etc/apt/keyrings/docker.asc'
+          ssh root@staging-ipv4.testrun.org 'echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian $(. /etc/os-release && echo $VERSION_CODENAME) stable" > /etc/apt/sources.list.d/docker.list'
+          ssh root@staging-ipv4.testrun.org 'apt-get update && apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin'
+
+      - name: prepare Docker bind mounts
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          ssh root@staging-ipv4.testrun.org 'mkdir -p /srv/chatmail/certs /srv/chatmail/dkim'
+          ssh root@staging-ipv4.testrun.org 'cp -a /var/lib/acme/. /srv/chatmail/certs/ && cp -a /etc/dkimkeys/. /srv/chatmail/dkim/' || true
+
+      - name: upload chatmail.ini for Docker
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          # Reuse chatmail.ini already created by the bare-metal deploy steps
+          ssh root@staging-ipv4.testrun.org "cp relay/chatmail.ini /srv/chatmail/chatmail.ini"
+
+      - name: deploy with Docker
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
+          GHCR_IMAGE="${{ env.REGISTRY }}/$(echo "${{ env.IMAGE_NAME }}" | tr '[:upper:]' '[:lower:]'):sha-${SHORT_SHA}"
+          rsync -avz --exclude='.git' --exclude='venv' --exclude='__pycache__' ./ root@staging-ipv4.testrun.org:/srv/chatmail/relay/
+          # Login to GHCR on VPS and pull pre-built image
+          echo "${{ secrets.GITHUB_TOKEN }}" | ssh root@staging-ipv4.testrun.org 'docker login ghcr.io -u ${{ github.actor }} --password-stdin'
+          ssh root@staging-ipv4.testrun.org "docker pull ${GHCR_IMAGE}"
+          ssh root@staging-ipv4.testrun.org "cd /srv/chatmail/relay && CHATMAIL_IMAGE=${GHCR_IMAGE} MAIL_DOMAIN=staging-ipv4.testrun.org docker compose -f docker/docker-compose.yaml -f docker/docker-compose.ci.yaml up -d"
+
+      - name: wait for container healthy
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          # Stream journald inside the container
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail journalctl -f --no-pager' &
+          LOG_PID=$!
+          trap "kill $LOG_PID 2>/dev/null || true" EXIT
+          for i in $(seq 1 60); do
+            status=$(ssh root@staging-ipv4.testrun.org 'docker inspect --format={{.State.Health.Status}} chatmail 2>/dev/null' || echo "missing")
+            echo "  [$i/60] status=$status"
+            if [ "$status" = "healthy" ]; then
+              echo "Container is healthy."
+              exit 0
+            fi
+            if [ "$status" = "unhealthy" ]; then
+              echo "Container is unhealthy!"
+              break
+            fi
+            sleep 5
+          done
+          echo "Container did not become healthy."
+          kill $LOG_PID 2>/dev/null || true
+          echo "--- failed units ---"
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail systemctl --failed --no-pager' || true
+          echo "--- service logs ---"
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail journalctl -u dovecot -u postfix -u nginx -u unbound --no-pager -n 50' || true
+          echo "--- listening ports ---"
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail ss -tlnp' || true
+          echo "--- chatmail.ini ---"
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail cat /etc/chatmail/chatmail.ini' || true
+          exit 1
+
+      - name: show container state
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          echo "--- listening ports ---"
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail ss -tlnp'
+          echo "--- chatmail.ini ---"
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail cat /etc/chatmail/chatmail.ini'
+
+      - name: Docker integration tests
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail cmdeploy test --slow --ssh-host @local'
+
+      - name: Docker DNS
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          # Reset zone file in case bare DNS already appended to it
+          git checkout .github/workflows/staging-ipv4.testrun.org-default.zone
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail chown opendkim:opendkim -R /etc/dkimkeys'
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail cmdeploy dns --ssh-host @local --zonefile /opt/chatmail/staging.zone --verbose'
+          ssh root@staging-ipv4.testrun.org 'docker cp chatmail:/opt/chatmail/staging.zone /tmp/staging.zone'
+          scp root@staging-ipv4.testrun.org:/tmp/staging.zone staging-generated.zone
+          cat staging-generated.zone >> .github/workflows/staging-ipv4.testrun.org-default.zone
+          cat .github/workflows/staging-ipv4.testrun.org-default.zone
+          scp .github/workflows/staging-ipv4.testrun.org-default.zone root@ns.testrun.org:/etc/nsd/staging-ipv4.testrun.org.zone
+          ssh root@ns.testrun.org nsd-checkzone staging-ipv4.testrun.org /etc/nsd/staging-ipv4.testrun.org.zone
+          ssh root@ns.testrun.org systemctl reload nsd
+
+      - name: Docker final DNS check
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: ssh root@staging-ipv4.testrun.org 'docker exec chatmail cmdeploy dns -v --ssh-host @local'
+
+      # --- Cleanup ---
+
+      - name: add SSH keys
+        if: >-
+          !cancelled()
+          && steps.wait-for-vps.outcome == 'success'
+        run: ssh root@staging-ipv4.testrun.org 'curl -s https://github.com/hpk42.keys https://github.com/j4n.keys >> .ssh/authorized_keys'
diff --git a/.github/workflows/test-and-deploy.yaml b/.github/workflows/test-and-deploy.yaml
index 2f744cb8e..18f34d12f 100644
--- a/.github/workflows/test-and-deploy.yaml
+++ b/.github/workflows/test-and-deploy.yaml
@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - j4n/docker-pr
   pull_request:
     paths-ignore:
       - 'scripts/**'
@@ -11,7 +12,67 @@ on:
       - 'CHANGELOG.md'
       - 'LICENSE'
 
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
 jobs:
+  build-docker:
+    name: Build Docker image
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    outputs:
+      image: ${{ steps.image-ref.outputs.image }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to GHCR
+        if: github.event_name == 'push'
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels)
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            # Tagged releases: v1.2.3 -> :1.2.3, :1.2, :latest
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            # Branch pushes: foo/docker-pr -> :foo-docker-pr
+            type=ref,event=branch
+            # Always: :sha-<hash>
+            type=sha
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: docker/chatmail_relay.dockerfile
+          push: ${{ github.event_name == 'push' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+          build-args: |
+            GIT_HASH=${{ github.sha }}
+
+      - name: Output image reference
+        id: image-ref
+        run: |
+          SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
+          IMAGE="${{ env.REGISTRY }}/$(echo "${{ env.IMAGE_NAME }}" | tr '[:upper:]' '[:lower:]'):sha-${SHORT_SHA}"
+          echo "image=${IMAGE}" >> "$GITHUB_OUTPUT"
+
   deploy:
     name: deploy on staging2.testrun.org, and run tests
     runs-on: ubuntu-latest
@@ -55,6 +116,7 @@ jobs:
         run: echo venv/bin >>$GITHUB_PATH
 
       - name: upload TLS cert after rebuilding
+        id: wait-for-vps
         run: |
           echo " --- wait until staging2.testrun.org VPS is rebuilt --- "
           rm ~/.ssh/known_hosts
@@ -71,8 +133,8 @@ jobs:
       - name: add hpk42 key to staging server
         run: ssh root@staging2.testrun.org 'curl -s https://github.com/hpk42.keys >> .ssh/authorized_keys'
 
-      - name: run deploy-chatmail offline tests 
-        run: pytest --pyargs cmdeploy 
+      - name: run deploy-chatmail offline tests
+        run: pytest --pyargs cmdeploy
 
       - run: |
           cmdeploy init staging2.testrun.org
@@ -95,3 +157,133 @@ jobs:
       - name: cmdeploy dns
         run: cmdeploy dns -v
 
+      # --- Docker deploy (push only, runs even if bare failed) ---
+
+      - name: stop bare services
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          ssh root@staging2.testrun.org 'systemctl stop postfix dovecot nginx opendkim unbound filtermail doveauth chatmail-metadata iroh-relay mtail fcgiwrap acmetool 2>/dev/null || true'
+
+      - name: install Docker on VPS
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          ssh root@staging2.testrun.org 'apt-get update && apt-get install -y ca-certificates curl'
+          ssh root@staging2.testrun.org 'install -m 0755 -d /etc/apt/keyrings'
+          ssh root@staging2.testrun.org 'curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc && chmod a+r /etc/apt/keyrings/docker.asc'
+          ssh root@staging2.testrun.org 'echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian $(. /etc/os-release && echo $VERSION_CODENAME) stable" > /etc/apt/sources.list.d/docker.list'
+          ssh root@staging2.testrun.org 'apt-get update && apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin'
+
+      - name: prepare Docker bind mounts
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          ssh root@staging2.testrun.org 'mkdir -p /srv/chatmail/certs /srv/chatmail/dkim'
+          ssh root@staging2.testrun.org 'cp -a /var/lib/acme/. /srv/chatmail/certs/ && cp -a /etc/dkimkeys/. /srv/chatmail/dkim/' || true
+
+      - name: upload chatmail.ini for Docker
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          # Reuse chatmail.ini already created by the bare-metal deploy steps
+          scp chatmail.ini root@staging2.testrun.org:/srv/chatmail/chatmail.ini
+
+      - name: deploy with Docker
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          SHORT_SHA=$(echo "${{ github.sha }}" | cut -c1-7)
+          GHCR_IMAGE="${{ env.REGISTRY }}/$(echo "${{ env.IMAGE_NAME }}" | tr '[:upper:]' '[:lower:]'):sha-${SHORT_SHA}"
+          rsync -avz --exclude='.git' --exclude='venv' --exclude='__pycache__' ./ root@staging2.testrun.org:/srv/chatmail/relay/
+          # Login to GHCR on VPS and pull pre-built image
+          echo "${{ secrets.GITHUB_TOKEN }}" | ssh root@staging2.testrun.org 'docker login ghcr.io -u ${{ github.actor }} --password-stdin'
+          ssh root@staging2.testrun.org "docker pull ${GHCR_IMAGE}"
+          ssh root@staging2.testrun.org "cd /srv/chatmail/relay && CHATMAIL_IMAGE=${GHCR_IMAGE} MAIL_DOMAIN=staging2.testrun.org docker compose -f docker/docker-compose.yaml -f docker/docker-compose.ci.yaml up -d"
+
+      - name: wait for container healthy
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          # Stream journald inside the container
+          ssh root@staging2.testrun.org 'docker exec chatmail journalctl -f --no-pager' &
+          LOG_PID=$!
+          trap "kill $LOG_PID 2>/dev/null || true" EXIT
+          for i in $(seq 1 60); do
+            status=$(ssh root@staging2.testrun.org 'docker inspect --format={{.State.Health.Status}} chatmail 2>/dev/null' || echo "missing")
+            echo "  [$i/60] status=$status"
+            if [ "$status" = "healthy" ]; then
+              echo "Container is healthy."
+              exit 0
+            fi
+            if [ "$status" = "unhealthy" ]; then
+              echo "Container is unhealthy!"
+              break
+            fi
+            sleep 5
+          done
+          echo "Container did not become healthy."
+          kill $LOG_PID 2>/dev/null || true
+          echo "--- failed units ---"
+          ssh root@staging2.testrun.org 'docker exec chatmail systemctl --failed --no-pager' || true
+          echo "--- service logs ---"
+          ssh root@staging2.testrun.org 'docker exec chatmail journalctl -u dovecot -u postfix -u nginx -u unbound --no-pager -n 50' || true
+          echo "--- listening ports ---"
+          ssh root@staging2.testrun.org 'docker exec chatmail ss -tlnp' || true
+          echo "--- chatmail.ini ---"
+          ssh root@staging2.testrun.org 'docker exec chatmail cat /etc/chatmail/chatmail.ini' || true
+          exit 1
+
+      - name: show container state
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          echo "--- listening ports ---"
+          ssh root@staging2.testrun.org 'docker exec chatmail ss -tlnp'
+          echo "--- chatmail.ini ---"
+          ssh root@staging2.testrun.org 'docker exec chatmail cat /etc/chatmail/chatmail.ini'
+
+      - name: Docker integration tests
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          ssh root@staging2.testrun.org 'docker exec chatmail cmdeploy test --slow --ssh-host @local'
+
+      - name: Docker DNS
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: |
+          # Reset zone file in case bare DNS already appended to it
+          git checkout .github/workflows/staging.testrun.org-default.zone
+          ssh root@staging2.testrun.org 'docker exec chatmail chown opendkim:opendkim -R /etc/dkimkeys'
+          ssh root@staging2.testrun.org 'docker exec chatmail cmdeploy dns --ssh-host @local --zonefile /opt/chatmail/staging.zone --verbose'
+          ssh root@staging2.testrun.org 'docker cp chatmail:/opt/chatmail/staging.zone /tmp/staging.zone'
+          scp root@staging2.testrun.org:/tmp/staging.zone staging-generated.zone
+          cat staging-generated.zone >> .github/workflows/staging.testrun.org-default.zone
+          cat .github/workflows/staging.testrun.org-default.zone
+          scp .github/workflows/staging.testrun.org-default.zone root@ns.testrun.org:/etc/nsd/staging2.testrun.org.zone
+          ssh root@ns.testrun.org nsd-checkzone staging2.testrun.org /etc/nsd/staging2.testrun.org.zone
+          ssh root@ns.testrun.org systemctl reload nsd
+
+      - name: Docker final DNS check
+        if: >-
+          !cancelled() && github.event_name == 'push'
+          && steps.wait-for-vps.outcome == 'success'
+        run: ssh root@staging2.testrun.org 'docker exec chatmail cmdeploy dns -v --ssh-host @local'
+
+      # --- Cleanup ---
+
+      - name: add SSH keys
+        if: >-
+          !cancelled()
+          && steps.wait-for-vps.outcome == 'success'
+        run: ssh root@staging2.testrun.org 'curl -s https://github.com/hpk42.keys https://github.com/j4n.keys >> .ssh/authorized_keys'
diff --git a/.gitignore b/.gitignore
index c0f40b9b1..db23c96e9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -164,3 +164,9 @@ cython_debug/
 #.idea/
 
 chatmail.zone
+
+# docker
+/data/
+/custom/
+docker/docker-compose.override.yaml
+docker/.env
diff --git a/cmdeploy/src/cmdeploy/cmdeploy.py b/cmdeploy/src/cmdeploy/cmdeploy.py
index aace16932..a070b096c 100644
--- a/cmdeploy/src/cmdeploy/cmdeploy.py
+++ b/cmdeploy/src/cmdeploy/cmdeploy.py
@@ -108,10 +108,7 @@ def run_cmd(args, out):
     pyinf = "pyinfra --dry" if args.dry_run else "pyinfra"
 
     cmd = f"{pyinf} --ssh-user root {ssh_host} {deploy_path} -y"
-    if ssh_host in ["localhost", "@docker"]:
-        if ssh_host == "@docker":
-            env["CHATMAIL_NOPORTCHECK"] = "True"
-            env["CHATMAIL_NOSYSCTL"] = "True"
+    if ssh_host == "localhost":
         cmd = f"{pyinf} @local {deploy_path} -y"
 
     if version.parse(pyinfra.__version__) < version.parse("3"):
@@ -316,7 +313,7 @@ def add_ssh_host_option(parser):
     parser.add_argument(
         "--ssh-host",
         dest="ssh_host",
-        help="Run commands on 'localhost', via '@docker', or on a specific SSH host "
+        help="Run commands on 'localhost' or on a specific SSH host "
         "instead of chatmail.ini's mail_domain.",
     )
 
@@ -378,9 +375,7 @@ def get_parser():
 
 def get_sshexec(ssh_host: str, verbose=True):
     if ssh_host in ["localhost", "@local"]:
-        return LocalExec(verbose, docker=False)
-    elif ssh_host == "@docker":
-        return LocalExec(verbose, docker=True)
+        return LocalExec(verbose)
     if verbose:
         print(f"[ssh] login to {ssh_host}")
     return SSHExec(ssh_host, verbose=verbose)
diff --git a/cmdeploy/src/cmdeploy/deployers.py b/cmdeploy/src/cmdeploy/deployers.py
index 11536062d..daf29ec0b 100644
--- a/cmdeploy/src/cmdeploy/deployers.py
+++ b/cmdeploy/src/cmdeploy/deployers.py
@@ -2,7 +2,6 @@
 Chat Mail pyinfra deploy.
 """
 
-import os
 import shutil
 import subprocess
 import sys
@@ -14,6 +13,7 @@
 from pyinfra.api import FactBase
 from pyinfra.facts import hardware
 from pyinfra.facts.files import Sha256File
+from pyinfra.facts.server import Command
 from pyinfra.facts.systemd import SystemdEnabled
 from pyinfra.operations import apt, files, pip, server, systemd
 
@@ -593,7 +593,7 @@ def deploy_chatmail(config_path: Path, disable_mail: bool, website_only: bool) -
             Out().red(f"Deploy failed: mtail_address {config.mtail_address} is not available (VPN up?).\n")
             exit(1)
 
-    if not os.environ.get("CHATMAIL_NOPORTCHECK"):
+    if host.get_fact(Command, "systemd-detect-virt -c || true") == "none":
         port_services = [
             (["master", "smtpd"], 25),
             ("unbound", 53),
diff --git a/cmdeploy/src/cmdeploy/dovecot/deployer.py b/cmdeploy/src/cmdeploy/dovecot/deployer.py
index 7a36d0a17..7230350b6 100644
--- a/cmdeploy/src/cmdeploy/dovecot/deployer.py
+++ b/cmdeploy/src/cmdeploy/dovecot/deployer.py
@@ -1,10 +1,9 @@
-import os
 import urllib.request
 
 from chatmaild.config import Config
 from pyinfra import host
 from pyinfra.facts.deb import DebPackages
-from pyinfra.facts.server import Arch, Sysctl
+from pyinfra.facts.server import Arch, Command, Sysctl
 from pyinfra.operations import apt, files, server, systemd
 
 from cmdeploy.basedeploy import (
@@ -140,19 +139,25 @@ def _configure_dovecot(config: Config, debug: bool = False) -> (bool, bool):
 
     # as per https://doc.dovecot.org/2.3/configuration_manual/os/
     # it is recommended to set the following inotify limits
-    if not os.environ.get("CHATMAIL_NOSYSCTL"):
-        for name in ("max_user_instances", "max_user_watches"):
-            key = f"fs.inotify.{name}"
-            if host.get_fact(Sysctl)[key] > 65535:
-                # Skip updating limits if already sufficient
-                # (enables running in incus containers where sysctl readonly)
-                continue
-            server.sysctl(
-                name=f"Change {key}",
-                key=key,
-                value=65535,
-                persist=True,
+    can_modify = host.get_fact(Command, "systemd-detect-virt -c || true") == "none"
+    for name in ("max_user_instances", "max_user_watches"):
+        key = f"fs.inotify.{name}"
+        value = host.get_fact(Sysctl)[key]
+        if value > 65534:
+            continue
+        if not can_modify:
+            print(
+                "\n!!!! refusing to attempt sysctl setting in shared-kernel containers\n"
+                f"!!!! dovecot: sysctl {key!r}={value}, should be >65534 for production setups\n"
+                "!!!!"
             )
+            continue
+        server.sysctl(
+            name=f"Change {key}",
+            key=key,
+            value=65535,
+            persist=True,
+        )
 
     timezone_env = files.line(
         name="Set TZ environment variable",
diff --git a/cmdeploy/src/cmdeploy/sshexec.py b/cmdeploy/src/cmdeploy/sshexec.py
index 7470d9277..6a37b9398 100644
--- a/cmdeploy/src/cmdeploy/sshexec.py
+++ b/cmdeploy/src/cmdeploy/sshexec.py
@@ -87,9 +87,8 @@ def logged(self, call, kwargs):
 class LocalExec:
     FuncError = FuncError
 
-    def __init__(self, verbose=False, docker=False):
+    def __init__(self, verbose=False):
         self.verbose = verbose
-        self.docker = docker
 
     def __call__(self, call, kwargs=None, log_callback=None):
         if kwargs is None:
@@ -101,10 +100,6 @@ def logged(self, call, kwargs: dict):
         if not title:
             title = call.__name__
         where = "locally"
-        if self.docker:
-            if call == remote.rdns.perform_initial_checks:
-                kwargs["pre_command"] = "docker exec chatmail "
-                where = "in docker"
         if self.verbose:
             print_stderr(f"Running {where}: {title}(**{kwargs})")
             return self(call, kwargs, log_callback=print_stderr)
diff --git a/doc/source/docker.rst b/doc/source/docker.rst
new file mode 100644
index 000000000..c8de5be00
--- /dev/null
+++ b/doc/source/docker.rst
@@ -0,0 +1,264 @@
+Docker installation
+===================
+
+This section provides instructions for installing a chatmail relay
+using Docker Compose.
+
+.. note::
+
+    - Docker support is experimental, CI builds and tests the image automatically, but please report bugs.
+    - The image wraps the cmdeploy process detailed in the :doc:`getting_started` instructions in a Debian-systemd image with r/w access to `/sys/fs`
+    - Currently amd64-only (arm64 should work but is untested).
+
+
+Setup Preparation
+-----------------
+
+We use ``chat.example.org`` as the chatmail domain in the following
+steps. Please substitute it with your own domain.
+
+1. Install docker and docker compose v2 (check with `docker compose version`), install, e.g., on
+    - Debian 12 through the `official install instructions <https://docs.docker.com/engine/install/debian/#install-using-the-repository>`_
+    - Debian 13+ with `apt install docker docker-compose`
+
+2. Setup the initial DNS records.
+   The following is an example in the familiar BIND zone file format with
+   a TTL of 1 hour (3600 seconds).
+   Please substitute your domain and IP addresses.
+
+   ::
+
+       chat.example.org. 3600 IN A 198.51.100.5
+       chat.example.org. 3600 IN AAAA 2001:db8::5
+       www.chat.example.org. 3600 IN CNAME chat.example.org.
+       mta-sts.chat.example.org. 3600 IN CNAME chat.example.org.
+
+3. Configure kernel parameters on the host, as these can not be set from the container::
+
+       echo "fs.inotify.max_user_instances=65536" | sudo tee -a /etc/sysctl.d/99-inotify.conf
+       echo "fs.inotify.max_user_watches=65536" | sudo tee -a /etc/sysctl.d/99-inotify.conf
+       sudo sysctl --system
+
+
+Docker Compose Setup
+--------------------
+
+Pre-built images are available from GitHub Container Registry. The
+``main`` branch and tagged releases are pushed automatically by CI::
+
+    docker pull ghcr.io/chatmail/relay:main      # latest main branch
+    docker pull ghcr.io/chatmail/relay:1.2.3     # tagged release
+
+
+Create service directory
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+Either:
+
+- Create a service directory and download the compose files::
+
+    mkdir -p /srv/chatmail-relay && cd /srv/chatmail-relay
+    wget https://raw.githubusercontent.com/chatmail/relay/refs/heads/main/docker/docker-compose.yaml
+    wget https://raw.githubusercontent.com/chatmail/relay/refs/heads/main/docker/docker-compose.override.yaml.example -O docker-compose.override.yaml
+
+- or clone the chatmail repo and enter the docker directory::
+
+   git clone https://github.com/chatmail/relay
+   cd relay/docker
+
+
+Customize and start
+^^^^^^^^^^^^^^^^^^^
+
+1. Set the fully qualified domain name of the relay::
+
+       echo 'MAIL_DOMAIN=chat.example.org' > .env
+
+   The container generates a ``chatmail.ini`` with defaults from
+   ``MAIL_DOMAIN`` on first start. To customize chatmail settings, mount
+   your own ``chatmail.ini`` instead (see `Custom chatmail.ini`_ below).
+
+2. All local customizations (data paths, extra volumes, config mounts) go in
+   ``docker-compose.override.yaml``, which Compose merges automatically with
+   the base file. By default, all data is stored in docker volumes, you will
+   likely want to at least create and configure the mail storage location, but
+   you might also want to configure external TLS certificates there.
+
+3. Start the container::
+
+       docker compose up -d
+       docker compose logs -f chatmail   # view logs, Ctrl+C to exit
+
+4. After installation is complete, open ``https://chat.example.org`` in
+   your browser.
+
+Finish install and test
+-----------------------
+
+You can test the installation with::
+
+        pip install cmping chat.example.org # or
+        uvx cmping chat.example.org # if you use https://docs.astral.sh/uv/
+
+You should check and extend your DNS records for better interoperability::
+
+    # Show required DNS records
+    docker exec chatmail cmdeploy dns --ssh-host @local
+
+You can check server status with::
+
+    docker exec chatmail cmdeploy status --ssh-host @local
+
+You can run some benchmarks (can also run from any machine with cmdeploy installed)::
+
+    docker exec chatmail cmdeploy bench
+
+You can run the test suite with::
+
+    docker exec chatmail cmdeploy test --ssh-host localhost
+
+You can look at logs::
+
+    docker exec chatmail journalctl -fu postfix@-
+
+
+Customization
+-------------
+
+Website
+^^^^^^^^^^^^^^
+
+You can customize the chatmail landing page by mounting a directory with
+your own website source files.
+
+1. Create a directory with your custom website source::
+
+       mkdir -p ./custom/www/src
+       nano ./custom/www/src/index.md
+
+2. Add the volume mount in ``docker-compose.override.yaml``::
+
+       services:
+         chatmail:
+           volumes:
+             - ./custom/www:/opt/chatmail-www
+
+3. Restart the service::
+
+       docker compose down
+       docker compose up -d
+
+
+Custom chatmail.ini
+^^^^^^^^^^^^^^^^^^^
+
+If you want to go beyond simply setting the ``MAIL_DOMAIN`` in ``.env``, you
+can use a regular `chatmail.ini` to give you full control.
+
+1. Extract the generated config from a running container::
+
+       docker cp chatmail:/etc/chatmail/chatmail.ini ./chatmail.ini
+
+2. Edit ``chatmail.ini`` as needed.
+
+3. Add the volume mount in ``docker-compose.override.yaml`` ::
+
+       services:
+         chatmail:
+           volumes:
+             - ./chatmail.ini:/etc/chatmail/chatmail.ini
+
+4. Restart the container, the container skips generating a new one: ::
+
+       docker compose down && docker compose up -d
+
+
+External TLS certificates
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If TLS certificates are managed outside the container (e.g. by certbot,
+acmetool, or Traefik on the host), mount them into the container and set
+``TLS_EXTERNAL_CERT_AND_KEY`` in ``docker-compose.override.yaml``.
+Changed certificates are picked up automatically via inotify.
+See the examples in the example override and :ref:`external-tls` in the getting started guide for details.
+
+
+Migrating from a bare-metal install
+------------------------------------
+
+If you have an existing bare-metal chatmail installation and want to
+switch to Docker:
+
+1. Stop all existing services::
+
+       systemctl stop postfix dovecot doveauth nginx opendkim unbound \
+         acmetool-redirector filtermail filtermail-incoming chatmail-turn \
+         iroh-relay chatmail-metadata lastlogin mtail
+       systemctl disable postfix dovecot doveauth nginx opendkim unbound \
+         acmetool-redirector filtermail filtermail-incoming chatmail-turn \
+         iroh-relay chatmail-metadata lastlogin mtail
+
+2. Copy your existing ``chatmail.ini`` and mount it into the container
+   (see `Custom chatmail.ini`_ above)::
+
+       cp /usr/local/lib/chatmaild/chatmail.ini ./chatmail.ini
+
+3. Copy persistent data into the ``./data/`` subdirectories (for example, as configured in `Customize and start`_) ::
+
+       mkdir -p data/dkim data/certs data/mail
+
+       # DKIM keys
+       cp -a /etc/dkimkeys/* data/dkim/
+
+       # TLS certificates
+       rsync -a /var/lib/acme/ data/certs/
+
+   Note that ownership of dkim and acme is adjusted on container start.
+
+   For the mail directory::
+
+       rsync -a /home/vmail/ data/mail/
+
+   Alternatively, mount ``/home/vmail`` directly by changing the volume
+   in ``docker-compose-override.yaml``::
+
+       - /home/vmail:/home/vmail
+
+   The three ``./data/`` subdirectories cover all persistent state.
+   Everything else is regenerated by the ``configure`` and ``activate``
+   stages on container start.
+
+Building the image
+------------------
+
+Clone the repository and build the Docker image::
+
+    git clone https://github.com/chatmail/relay
+    cd relay
+    docker/build.sh
+
+The build bakes all binaries, Python packages, and the install stage
+into the image. After building, only the ``docker/`` directory and a ``.env``
+with ``MAIL_DOMAIN`` are needed to run the container. The `build.sh` passes the
+git hash onto the docker build so it can be determined if there has been a
+change that warrants a redeploy.
+
+You can transfer a locally built image to your server directly (pigz is parallel `gzip` which can be used instead as well) ::
+
+    docker save chatmail-relay:latest | pigz | ssh chat.example.org 'pigz -d | docker load'
+
+
+Forcing a full reinstall
+------------------------
+
+On container start, only the ``configure`` and ``activate`` stages run by default.
+
+To force a full reinstall (e.g. after updating the source), either
+rebuild the image::
+
+    docker compose build chatmail
+    docker compose up -d
+
+Or override the stages at runtime without rebuilding::
+
+    CMDEPLOY_STAGES="install,configure,activate" docker compose up -d
diff --git a/doc/source/getting_started.rst b/doc/source/getting_started.rst
index 28781f28e..259d31b6e 100644
--- a/doc/source/getting_started.rst
+++ b/doc/source/getting_started.rst
@@ -98,6 +98,12 @@ steps. Please substitute it with your own domain.
    configure at your DNS provider (it can take some time until they are
    public).
 
+Docker installation
+-------------------
+
+There is experimental support for running chatmail via Docker Compose.
+See :doc:`docker` for full setup instructions.
+
 Other helpful commands
 ----------------------
 
diff --git a/doc/source/index.rst b/doc/source/index.rst
index d37a10f68..2ff585997 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -13,6 +13,7 @@ Contributions and feedback welcome through the https://github.com/chatmail/relay
     :maxdepth: 5
 
     getting_started
+    docker
     proxy
     migrate
     overview
diff --git a/docker/build.sh b/docker/build.sh
new file mode 100755
index 000000000..04fa97aa2
--- /dev/null
+++ b/docker/build.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+# Build the chatmail Docker image with the current git hash baked in.
+# Usage: ./docker/build.sh [extra docker-compose build args...]
+#
+# .git/ is excluded from the build context (.dockerignore) so the hash
+# must be passed as a build arg from the host.
+
+export GIT_HASH=$(git rev-parse HEAD)
+exec docker compose -f docker/docker-compose.yaml build "$@"
diff --git a/docker/chatmail-init.service b/docker/chatmail-init.service
new file mode 100644
index 000000000..9e0a517b3
--- /dev/null
+++ b/docker/chatmail-init.service
@@ -0,0 +1,14 @@
+[Unit]
+Description=Run container setup commands
+After=multi-user.target
+ConditionPathExists=/chatmail-init.sh
+
+[Service]
+Type=oneshot
+ExecStart=/bin/bash /chatmail-init.sh
+RemainAfterExit=true
+WorkingDirectory=/opt/chatmail
+PassEnvironment=<envs_list>
+
+[Install]
+WantedBy=multi-user.target
diff --git a/docker/chatmail-init.sh b/docker/chatmail-init.sh
new file mode 100755
index 000000000..32daff590
--- /dev/null
+++ b/docker/chatmail-init.sh
@@ -0,0 +1,85 @@
+#!/bin/bash
+
+set -euo pipefail
+export CHATMAIL_INI="${CHATMAIL_INI:-/etc/chatmail/chatmail.ini}"
+
+CMDEPLOY=/opt/cmdeploy/bin/cmdeploy
+
+if [ -z "$MAIL_DOMAIN" ]; then
+    echo "ERROR: Environment variable 'MAIL_DOMAIN' must be set!" >&2
+    exit 1
+fi
+
+# Generate DKIM keys if not mounted
+if [ ! -f /etc/dkimkeys/opendkim.private ]; then
+    /usr/sbin/opendkim-genkey -D /etc/dkimkeys -d "$MAIL_DOMAIN" -s opendkim
+fi
+# Fix ownership for bind-mounted keys (host opendkim UID may differ from container)
+chown -R opendkim:opendkim /etc/dkimkeys
+
+# Create chatmail.ini, skip if mounted
+mkdir -p "$(dirname "$CHATMAIL_INI")"
+if [ ! -f "$CHATMAIL_INI" ]; then
+    $CMDEPLOY init --config "$CHATMAIL_INI" "$MAIL_DOMAIN"
+fi
+
+# Auto-detect IPv6: if the host has no IPv6 connectivity, set disable_ipv6
+# in the ini so dovecot/postfix/nginx bind to IPv4 only.
+# Uses network_mode:host so /proc/net/if_inet6 reflects the host's stack.
+if [ ! -e /proc/net/if_inet6 ]; then
+    if grep -q '^disable_ipv6 = False' "$CHATMAIL_INI"; then
+        sed -i 's/^disable_ipv6 = False/disable_ipv6 = True/' "$CHATMAIL_INI"
+        echo "[INFO] IPv6 not available, set disable_ipv6 = True"
+    fi
+fi
+
+# Inject external TLS paths from env var unless defined in chatmail.ini
+if [ -n "${TLS_EXTERNAL_CERT_AND_KEY:-}" ]; then
+    if ! grep -q '^tls_external_cert_and_key' "$CHATMAIL_INI"; then
+        echo "tls_external_cert_and_key = $TLS_EXTERNAL_CERT_AND_KEY" >> "$CHATMAIL_INI"
+    fi
+fi
+
+# Ensure mailboxes directory exists (chatmail-metadata needs it at startup,
+# but Dovecot only creates it on first mail delivery)
+mkdir -p "/home/vmail/mail/${MAIL_DOMAIN}"
+chown vmail:vmail "/home/vmail/mail/${MAIL_DOMAIN}"
+
+# --- Deploy fingerprint: skip cmdeploy run if nothing changed ---
+# On restart with identical image+config, systemd already brings up all
+# enabled services only configure+activate are needed here.
+IMAGE_VERSION_FILE="/etc/chatmail-image-version"
+FINGERPRINT_FILE="/etc/chatmail/.deploy-fingerprint"
+image_ver="none"
+[ -f "$IMAGE_VERSION_FILE" ] && image_ver=$(cat "$IMAGE_VERSION_FILE")
+config_hash=$(sha256sum "$CHATMAIL_INI" | cut -c1-16)
+current_fp="${image_ver}:${config_hash}"
+
+# CMDEPLOY_STAGES non-empty in env = operator override -> always run.
+# Otherwise, if fingerprint matches the last successful deploy, skip.
+if [ -z "${CMDEPLOY_STAGES:-}" ] \
+    && [ -f "$FINGERPRINT_FILE" ] \
+    && [ "$(cat "$FINGERPRINT_FILE")" = "$current_fp" ]; then
+    echo "[INFO] No changes detected ($current_fp), skipping deploy."
+else
+    export CMDEPLOY_STAGES="${CMDEPLOY_STAGES:-configure,activate}"
+
+    # Skip DNS check when MAIL_DOMAIN is a bare IP address
+    SKIP_DNS=""
+    if [[ "$MAIL_DOMAIN" =~ ^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$ ]] || [[ "$MAIL_DOMAIN" =~ : ]]; then
+        SKIP_DNS="--skip-dns-check"
+    fi
+    $CMDEPLOY run --config "$CHATMAIL_INI" --ssh-host @local $SKIP_DNS
+
+    # Restore the build-time hash
+    cp /etc/chatmail-image-version /etc/chatmail-version
+    echo "$current_fp" > "$FINGERPRINT_FILE"
+fi
+
+# Signal success to Docker healthcheck
+touch /run/chatmail-init.done
+
+# Forward journald to console so `docker compose logs` works
+grep -q '^ForwardToConsole=yes' /etc/systemd/journald.conf \
+    || echo "ForwardToConsole=yes" >> /etc/systemd/journald.conf
+systemctl restart systemd-journald
diff --git a/docker/chatmail_relay.dockerfile b/docker/chatmail_relay.dockerfile
new file mode 100644
index 000000000..2e91f9ba7
--- /dev/null
+++ b/docker/chatmail_relay.dockerfile
@@ -0,0 +1,108 @@
+# syntax=docker/dockerfile:1
+FROM jrei/systemd-debian:12 AS base
+
+ENV LANG=en_US.UTF-8
+
+RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
+    --mount=type=cache,target=/var/lib/apt/lists,sharing=locked \
+    echo 'APT::Install-Recommends "0";' > /etc/apt/apt.conf.d/01norecommend && \
+    echo 'APT::Install-Suggests "0";' >> /etc/apt/apt.conf.d/01norecommend && \
+    apt-get update && \
+    DEBIAN_FRONTEND=noninteractive TZ=UTC \
+    apt-get install -y \
+        ca-certificates \
+        gcc \
+        git \
+        python3 \
+        python3-dev \
+        python3-venv \
+        tzdata \
+        locales && \
+    sed -i -e "s/# $LANG.*/$LANG UTF-8/" /etc/locale.gen && \
+    dpkg-reconfigure --frontend=noninteractive locales && \
+    update-locale LANG=$LANG
+
+# --- Build-time: install cmdeploy venv and run install stage ---
+# Editable install so importlib.resources reads directly from the source tree.
+# On container start only "configure,activate" stages run.
+
+# Copy dependency metadata first so pip install layer is cached
+COPY cmdeploy/pyproject.toml /opt/chatmail/cmdeploy/pyproject.toml
+COPY chatmaild/pyproject.toml /opt/chatmail/chatmaild/pyproject.toml
+
+# Dummy scaffolding so editable install can discover packages
+RUN mkdir -p /opt/chatmail/cmdeploy/src/cmdeploy \
+             /opt/chatmail/chatmaild/src/chatmaild && \
+    touch /opt/chatmail/cmdeploy/src/cmdeploy/__init__.py \
+          /opt/chatmail/chatmaild/src/chatmaild/__init__.py
+
+# Dummy git repo: .git/ is excluded from the build context (.dockerignore)
+# but setuptools calls `git ls-files` when building the sdist.
+WORKDIR /opt/chatmail
+RUN --mount=type=cache,target=/root/.cache/pip \
+    git init -q && \
+    python3 -m venv /opt/cmdeploy && \
+    /opt/cmdeploy/bin/pip install -e chatmaild/ -e cmdeploy/
+
+# Full source copy (editable install's .egg-link still points here)
+COPY . /opt/chatmail/
+
+# Minimal chatmail.ini
+RUN printf '[params]\nmail_domain = build.local\n' > /tmp/chatmail.ini
+
+RUN CMDEPLOY_STAGES=install \
+    CHATMAIL_INI=/tmp/chatmail.ini \
+    /opt/cmdeploy/bin/pyinfra @local \
+        /opt/chatmail/cmdeploy/src/cmdeploy/run.py -y
+
+RUN cp -a www/ /opt/chatmail-www/
+
+# Remove build-only packages — not needed at runtime.
+# Keep git: test_deployed_state needs `git rev-parse HEAD` to verify the
+# deployed version hash matches /etc/chatmail-version.
+RUN apt-get purge -y gcc python3-dev && \
+    apt-get autoremove -y && \
+    rm -f /tmp/chatmail.ini
+
+# Record image version (used in deploy fingerprint at runtime).
+# GIT_HASH is passed as a build arg (from docker-compose or CI) so that
+# .git/ can be excluded from the build context via .dockerignore.
+# Two files: chatmail-image-version is the immutable build hash (survives
+# deploys); chatmail-version is overwritten by cmdeploy run and restored
+# from the image version after each deploy in chatmail-init.sh.
+ARG GIT_HASH=unknown
+RUN echo "$GIT_HASH" > /etc/chatmail-image-version && \
+    echo "$GIT_HASH" > /etc/chatmail-version
+
+# Mock git HEAD so `git rev-parse HEAD` returns the source repo's commit hash.
+# The .git/ dir was created by `git init` earlier (for setuptools); we just
+# write the build hash into whatever branch HEAD points to.
+RUN head_ref=$(sed 's/^ref: //' /opt/chatmail/.git/HEAD) && \
+    mkdir -p "/opt/chatmail/.git/$(dirname "$head_ref")" && \
+    echo "$GIT_HASH" > "/opt/chatmail/.git/$head_ref"
+# --- End build-time install ---
+
+ENV TZ=:/etc/localtime
+ENV PATH="/opt/cmdeploy/bin:${PATH}"
+RUN ln -s /etc/chatmail/chatmail.ini /opt/chatmail/chatmail.ini
+
+ARG CHATMAIL_INIT_SERVICE_PATH=/lib/systemd/system/chatmail-init.service
+COPY ./docker/chatmail-init.service "$CHATMAIL_INIT_SERVICE_PATH"
+RUN ln -sf "$CHATMAIL_INIT_SERVICE_PATH" "/etc/systemd/system/multi-user.target.wants/chatmail-init.service"
+
+# Remove default nginx site config at build time (not in entrypoint)
+RUN rm -f /etc/nginx/sites-enabled/default
+
+COPY --chmod=555 ./docker/chatmail-init.sh /chatmail-init.sh
+COPY --chmod=555 ./docker/entrypoint.sh /entrypoint.sh
+COPY --chmod=555 ./docker/healthcheck.sh /healthcheck.sh
+
+HEALTHCHECK --interval=10s --start-period=180s --timeout=10s --retries=3 \
+  CMD /healthcheck.sh
+
+STOPSIGNAL SIGRTMIN+3
+
+ENTRYPOINT ["/entrypoint.sh"]
+
+CMD [   "--default-standard-output=journal+console", \
+        "--default-standard-error=journal+console" ]
diff --git a/docker/docker-compose-traefik.yaml b/docker/docker-compose-traefik.yaml
new file mode 100644
index 000000000..2964fcce8
--- /dev/null
+++ b/docker/docker-compose-traefik.yaml
@@ -0,0 +1,70 @@
+# Traefik reverse-proxy example — use as a compose override:
+#
+#   docker compose -f docker-compose.yaml -f docker-compose-traefik.yaml up -d
+#
+# Traefik handles HTTP→HTTPS redirect and ACME certificate issuance.
+# traefik-certs-dumper extracts the certificates to the filesystem so
+# chatmail's Postfix/Dovecot/nginx can use them via TLS_EXTERNAL_CERT_AND_KEY.
+#
+# Prerequisites:
+#   mkdir -p traefik/data traefik/dynamic-configs
+#   touch traefik/data/acme.json && chmod 600 traefik/data/acme.json
+#   cp traefik/config.yaml.example traefik/config.yaml   # see below
+#
+# Required .env variables (in addition to MAIL_DOMAIN):
+#   ACME_EMAIL=admin@example.org
+
+services:
+  chatmail:
+    environment:
+      # Point chatmail at the certs dumped by traefik-certs-dumper.
+      # The container's tls-cert-reload.path watches for changes.
+      TLS_EXTERNAL_CERT_AND_KEY: >-
+        /traefik-certs/${MAIL_DOMAIN}/certificate.crt
+        /traefik-certs/${MAIL_DOMAIN}/privatekey.key
+    volumes:
+      - traefik-certs:/traefik-certs:ro
+    depends_on:
+      - traefik-certs-dumper
+    labels:
+      - traefik.enable=true
+      - traefik.http.services.chatmail.loadbalancer.server.scheme=https
+      - traefik.http.services.chatmail.loadbalancer.server.port=443
+      - traefik.http.routers.chatmail.rule=Host(`${MAIL_DOMAIN}`) || Host(`mta-sts.${MAIL_DOMAIN}`) || Host(`www.${MAIL_DOMAIN}`)
+      - traefik.http.routers.chatmail.tls=true
+      - traefik.http.routers.chatmail.tls.certresolver=letsEncrypt
+
+  traefik:
+    image: traefik:v3.3
+    container_name: traefik
+    restart: unless-stopped
+    network_mode: host
+    command:
+      - "--configFile=/config.yaml"
+      - "--certificatesresolvers.letsEncrypt.acme.email=${ACME_EMAIL}"
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+      - ./traefik/config.yaml:/config.yaml:ro
+      - ./traefik/data/acme.json:/acme.json
+      - ./traefik/dynamic-configs:/dynamic/conf:ro
+
+  traefik-certs-dumper:
+    image: ldez/traefik-certs-dumper:v2.10.0
+    restart: unless-stopped
+    depends_on:
+      - traefik
+    entrypoint: sh -c '
+      apk add openssl
+      && while ! [ -e /data/acme.json ]
+         || ! [ $$(jq ".[] | .Certificates | length" /data/acme.json | jq -s "add") != 0 ]; do
+           sleep 1;
+         done
+      && traefik-certs-dumper file
+           --version v3 --watch --domain-subdir=true
+           --source /data/acme.json --dest /certs'
+    volumes:
+      - ./traefik/data/acme.json:/data/acme.json:ro
+      - traefik-certs:/certs
+
+volumes:
+  traefik-certs:
diff --git a/docker/docker-compose.ci.yaml b/docker/docker-compose.ci.yaml
new file mode 100644
index 000000000..760ad4519
--- /dev/null
+++ b/docker/docker-compose.ci.yaml
@@ -0,0 +1,11 @@
+# Used by .github/workflows/docker-ci.yaml
+# The GHCR image is set via CHATMAIL_IMAGE env var at deploy time.
+services:
+  chatmail:
+    image: ${CHATMAIL_IMAGE:-chatmail-relay:latest}
+    volumes:
+      - /srv/chatmail/chatmail.ini:/etc/chatmail/chatmail.ini
+      - /srv/chatmail/dkim:/etc/dkimkeys
+      - /srv/chatmail/certs:/var/lib/acme
+    environment:
+      TLS_EXTERNAL_CERT_AND_KEY: /var/lib/acme/live/${MAIL_DOMAIN}/fullchain /var/lib/acme/live/${MAIL_DOMAIN}/privkey
diff --git a/docker/docker-compose.override.yaml.example b/docker/docker-compose.override.yaml.example
new file mode 100644
index 000000000..c7ad53696
--- /dev/null
+++ b/docker/docker-compose.override.yaml.example
@@ -0,0 +1,44 @@
+# Local overrides: copy to docker-compose.override.yaml in this directory.
+# Compose automatically merges this with docker-compose.yaml.
+#
+#   cp docker-compose.override.yaml.example docker-compose.override.yaml
+#
+# Volumes are APPENDED to the base file's volumes list, environment and other scalar keys are MERGED by key.
+services:
+  chatmail:
+    volumes:
+      ## Data paths — bind-mount to host directories for easy access/backup.
+
+      # - ./data/dkim:/etc/dkimkeys
+      # - ./data/certs:/var/lib/acme
+
+      # - ./data/mail:/home/vmail
+      ## Or mount from an existing bare-metal install.
+      # - /home/vmail:/home/vmail
+
+      ## Mount your own chatmail.ini (skips auto-generation):
+      # - ./chatmail.ini:/etc/chatmail/chatmail.ini
+
+      ## Custom website:
+      # - ./custom/www:/opt/chatmail-www
+
+      ## Debug — mount scripts for live editing:
+      # - ./chatmail-init.sh:/chatmail-init.sh
+      # - ./entrypoint.sh:/entrypoint.sh
+
+    # environment:
+      ## Mount certs (above) and set TLS_EXTERNAL_CERT_AND_KEY to in-container paths.
+      ## A tls-cert-reload.path watcher inside the container reloads services
+      ## when the cert file changes. However, inotify does not cross bind-mount
+      ## boundaries, so host-side renewals (certbot, acmetool, etc.) must
+      ## notify the container explicitly. Add this to your renewal hook:
+      ##
+      ##   docker exec chatmail systemctl start tls-cert-reload.service
+      ##
+      ## Host acmetool (bare-metal migration): create mount above, and
+      ##   rsync -a /var/lib/acme/live data/certs
+      # TLS_EXTERNAL_CERT_AND_KEY: "/var/lib/acme/live/${MAIL_DOMAIN}/fullchain /var/lib/acme/live/${MAIL_DOMAIN}/privkey"
+      ##
+      ## (Untested) Traefik certs-dumper (see docker/docker-compose-traefik.yaml) - also add volume:
+      ##   - traefik-certs:/certs:ro
+      # TLS_EXTERNAL_CERT_AND_KEY: "/certs/${MAIL_DOMAIN}/certificate.crt /certs/${MAIL_DOMAIN}/privatekey.key"
diff --git a/docker/docker-compose.yaml b/docker/docker-compose.yaml
new file mode 100644
index 000000000..8ec99e684
--- /dev/null
+++ b/docker/docker-compose.yaml
@@ -0,0 +1,48 @@
+# Base compose file — do not edit. Put customizations (data paths, extra
+# volumes, env overrides) in docker-compose.override.yaml instead.
+# See docker-compose.override.yaml.example in this directory for a starting point.
+#
+# Security notes: this container uses 
+#  - network_mode:host chatmail needs many ports (25, 53, 80, 143, 443, 465,
+#  587, 993, 3340, 8443) and needs to operate from the real IP, which bridging
+#  would make tricky
+#  - cgroup:host (required for systemd). 
+#  Together these give the container near-host-level access. This is acceptable
+#  for a dedicated mail server, but be aware that the container can bind any
+#  port and see all host network traffic.
+
+services:
+  chatmail:
+    build:
+      context: ../
+      dockerfile: docker/chatmail_relay.dockerfile
+      args:
+        GIT_HASH: ${GIT_HASH:-unknown}
+    image: chatmail-relay:latest
+    restart: unless-stopped
+    container_name: chatmail
+    # Required for systemd — use only one of the following:
+    cgroup: host          # compose v2
+    # privileged: true    # compose v1 (less restricted)
+    tty: true # required for logs
+    tmpfs: # required for systemd
+      - /tmp
+      - /run
+      - /run/lock
+    logging:
+      driver: none
+    environment:
+      MAIL_DOMAIN: $MAIL_DOMAIN
+    network_mode: "host"
+    volumes:
+      ## system (required)
+      - /sys/fs/cgroup:/sys/fs/cgroup:rw
+      ## data (defaults — override in docker-compose.override.yaml)
+      - mail:/home/vmail
+      - dkim:/etc/dkimkeys
+      - certs:/var/lib/acme
+
+volumes:
+  mail:
+  dkim:
+  certs:
diff --git a/docker/entrypoint.sh b/docker/entrypoint.sh
new file mode 100755
index 000000000..3e0e348a7
--- /dev/null
+++ b/docker/entrypoint.sh
@@ -0,0 +1,9 @@
+#!/bin/bash
+set -eo pipefail
+
+CHATMAIL_INIT_SERVICE_PATH="${CHATMAIL_INIT_SERVICE_PATH:-/lib/systemd/system/chatmail-init.service}"
+
+env_vars="MAIL_DOMAIN CMDEPLOY_STAGES CHATMAIL_INI TLS_EXTERNAL_CERT_AND_KEY PATH"
+sed -i "s|<envs_list>|$env_vars|g" "$CHATMAIL_INIT_SERVICE_PATH"
+
+exec /lib/systemd/systemd "$@"
diff --git a/docker/env.example b/docker/env.example
new file mode 100644
index 000000000..3eebb3731
--- /dev/null
+++ b/docker/env.example
@@ -0,0 +1 @@
+MAIL_DOMAIN=chat.example.com
diff --git a/docker/healthcheck.sh b/docker/healthcheck.sh
new file mode 100644
index 000000000..88d9f8067
--- /dev/null
+++ b/docker/healthcheck.sh
@@ -0,0 +1,16 @@
+#!/bin/bash
+# returns 0 when chatmail-init succeeded and all expected services are running.
+
+set -e
+
+test -f /run/chatmail-init.done
+
+# Core services
+services="chatmail-metadata doveauth dovecot filtermail filtermail-incoming nginx postfix unbound"
+
+# Optional services
+for svc in iroh-relay turnserver; do
+    systemctl is-enabled "$svc" 2>/dev/null && services="$services $svc"
+done
+
+exec systemctl is-active $services