diff --git a/.github/workflows/docker-ci.yaml b/.github/workflows/docker-ci.yaml
new file mode 100644
index 00000000..634c6e79
--- /dev/null
+++ b/.github/workflows/docker-ci.yaml
@@ -0,0 +1,344 @@
+name: Docker CI
+
+on:
+  pull_request:
+    paths:
+      - 'docker/**'
+      - 'docker-compose.yaml'
+      - '.dockerignore'
+      - 'chatmaild/**'
+      - 'cmdeploy/**'
+      - '.github/workflows/docker-ci.yaml'
+  push:
+    branches:
+      - main
+      - j4n/docker-pr
+    paths:
+      - 'docker/**'
+      - 'docker-compose.yaml'
+      - '.dockerignore'
+      - 'chatmaild/**'
+      - 'cmdeploy/**'
+      - '.github/workflows/docker-ci.yaml'
+    tags:
+      - 'v*'
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build:
+    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: j4n/docker → :j4n-docker
+            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-staging2:
+    name: Deploy to staging2.testrun.org
+    needs: build
+    if: github.event_name == 'push'
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    environment:
+      name: staging2.testrun.org
+      url: https://staging2.testrun.org/
+    concurrency: staging2.testrun.org
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: prepare SSH
+        run: |
+          mkdir ~/.ssh
+          echo "${{ secrets.STAGING_SSH_KEY }}" >> ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+          ssh-keyscan staging2.testrun.org > ~/.ssh/known_hosts
+          # save previous acme & dkim state
+          rsync -avz root@staging2.testrun.org:/var/lib/acme . || true
+          rsync -avz root@staging2.testrun.org:/etc/dkimkeys . || true
+          # store previous acme & dkim state on ns.testrun.org, if it contains useful certs
+          if [ -f dkimkeys/opendkim.private ]; then rsync -avz -e "ssh -o StrictHostKeyChecking=accept-new" dkimkeys root@ns.testrun.org:/tmp/ || true; fi
+          if [ "$(ls -A acme/certs)" ]; then rsync -avz -e "ssh -o StrictHostKeyChecking=accept-new" acme root@ns.testrun.org:/tmp/ || true; fi
+          # make sure CAA record isn't set
+          scp -o StrictHostKeyChecking=accept-new .github/workflows/staging.testrun.org-default.zone root@ns.testrun.org:/etc/nsd/staging2.testrun.org.zone
+          ssh root@ns.testrun.org sed -i '/CAA/d' /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: rebuild staging2.testrun.org to have a clean VPS
+        run: |
+            curl -X POST \
+            -H "Authorization: Bearer ${{ secrets.HETZNER_API_TOKEN }}" \
+            -H "Content-Type: application/json" \
+            -d '{"image":"debian-12"}' \
+            "https://api.hetzner.cloud/v1/servers/${{ secrets.STAGING_SERVER_ID }}/actions/rebuild"
+
+      - name: wait for VPS rebuild
+        run: |
+          rm ~/.ssh/known_hosts
+          while ! ssh -o ConnectTimeout=180 -o StrictHostKeyChecking=accept-new root@staging2.testrun.org id -u ; do sleep 1 ; done
+
+      - run: scripts/initenv.sh
+      - name: append venv/bin to PATH
+        run: echo venv/bin >>$GITHUB_PATH
+
+      - name: install Docker on VPS
+        run: |
+          ssh root@staging2.testrun.org 'apt-get update && apt-get install -y ca-certificates curl'
+          ssh root@staging2.testrun.org 'install -m 0755 -d /etc/apt/keyrings'
+          ssh root@staging2.testrun.org 'curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc && chmod a+r /etc/apt/keyrings/docker.asc'
+          ssh root@staging2.testrun.org 'echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian $(. /etc/os-release && echo $VERSION_CODENAME) stable" > /etc/apt/sources.list.d/docker.list'
+          ssh root@staging2.testrun.org 'apt-get update && apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin'
+
+      - name: restore ACME & DKIM state
+        run: |
+          # download from ns.testrun.org
+          rsync -e "ssh -o StrictHostKeyChecking=accept-new" -avz root@ns.testrun.org:/tmp/acme acme-restore || true
+          rsync -avz root@ns.testrun.org:/tmp/dkimkeys dkimkeys-restore || true
+          # restore to VPS host paths (will be bind-mounted into container)
+          ssh root@staging2.testrun.org mkdir -p /srv/chatmail/dkim /srv/chatmail/certs
+          rsync -avz acme-restore/acme/ root@staging2.testrun.org:/srv/chatmail/certs/ || true
+          rsync -avz dkimkeys-restore/dkimkeys/ root@staging2.testrun.org:/srv/chatmail/dkim/ || true
+
+      - name: generate chatmail.ini
+        run: |
+          cmdeploy init staging2.testrun.org
+          sed -i 's/#\s*mtail_address/mtail_address/' chatmail.ini
+          scp chatmail.ini root@staging2.testrun.org:/srv/chatmail/chatmail.ini
+
+      - name: upload repo and deploy with Docker
+        run: |
+          GHCR_IMAGE="${{ needs.build.outputs.image }}"
+          rsync -avz --exclude='.git' --exclude='venv' --exclude='__pycache__' ./ root@staging2.testrun.org:/srv/chatmail/relay/
+          # Override: bind-mount data dirs + custom chatmail.ini + pre-built image
+          ssh root@staging2.testrun.org "cat > /srv/chatmail/relay/docker-compose.override.yaml << EOF
+          services:
+            chatmail:
+              image: ${GHCR_IMAGE}
+              volumes:
+                - /srv/chatmail/dkim:/etc/dkimkeys
+                - /srv/chatmail/certs:/var/lib/acme
+                - /srv/chatmail/chatmail.ini:/etc/chatmail/chatmail.ini
+          EOF"
+          # Login to GHCR on VPS and pull pre-built image
+          echo "${{ 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 && MAIL_DOMAIN=staging2.testrun.org docker compose up -d'
+
+      - name: wait for container to become healthy
+        run: |
+          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
+            sleep 5
+          done
+          echo "Container did not become healthy in time."
+          ssh root@staging2.testrun.org 'cd /srv/chatmail/relay && docker compose logs --tail=200'
+          exit 1
+
+      - 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: set DNS entries
+        run: |
+          ssh root@staging2.testrun.org chown opendkim:opendkim -R /srv/chatmail/dkim
+          # run cmdeploy dns inside the container
+          ssh root@staging2.testrun.org 'docker exec chatmail cmdeploy dns --ssh-host @local --zonefile /tmp/staging.zone --verbose'
+          ssh root@staging2.testrun.org 'docker cp chatmail:/tmp/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: cmdeploy test
+        run: CHATMAIL_DOMAIN2=ci-chatmail.testrun.org cmdeploy test --slow
+
+      - name: cmdeploy dns
+        run: |
+          ssh root@staging2.testrun.org 'docker exec chatmail cmdeploy dns -v --ssh-host @local'
+
+  deploy-staging-ipv4:
+    name: Deploy to staging-ipv4.testrun.org
+    needs: build
+    if: github.event_name == 'push'
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    environment:
+      name: staging-ipv4.testrun.org
+      url: https://staging-ipv4.testrun.org/
+    concurrency: staging-ipv4.testrun.org
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: prepare SSH
+        run: |
+          mkdir ~/.ssh
+          echo "${{ secrets.STAGING_SSH_KEY }}" >> ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+          ssh-keyscan staging-ipv4.testrun.org > ~/.ssh/known_hosts
+          # save previous acme & dkim state
+          rsync -avz root@staging-ipv4.testrun.org:/var/lib/acme acme-ipv4 || true
+          rsync -avz root@staging-ipv4.testrun.org:/etc/dkimkeys dkimkeys-ipv4 || true
+          # store previous acme & dkim state on ns.testrun.org, if it contains useful certs
+          if [ -f dkimkeys-ipv4/dkimkeys/opendkim.private ]; then rsync -avz -e "ssh -o StrictHostKeyChecking=accept-new" dkimkeys-ipv4 root@ns.testrun.org:/tmp/ || true; fi
+          if [ "$(ls -A acme-ipv4/acme/certs)" ]; then rsync -avz -e "ssh -o StrictHostKeyChecking=accept-new" acme-ipv4 root@ns.testrun.org:/tmp/ || true; fi
+          # make sure CAA record isn't set
+          scp -o StrictHostKeyChecking=accept-new .github/workflows/staging-ipv4.testrun.org-default.zone root@ns.testrun.org:/etc/nsd/staging-ipv4.testrun.org.zone
+          ssh root@ns.testrun.org sed -i '/CAA/d' /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: rebuild staging-ipv4.testrun.org to have a clean VPS
+        run: |
+            curl -X POST \
+            -H "Authorization: Bearer ${{ secrets.HETZNER_API_TOKEN }}" \
+            -H "Content-Type: application/json" \
+            -d '{"image":"debian-12"}' \
+            "https://api.hetzner.cloud/v1/servers/${{ secrets.STAGING_IPV4_SERVER_ID }}/actions/rebuild"
+
+      - run: scripts/initenv.sh
+      - name: append venv/bin to PATH
+        run: echo venv/bin >>$GITHUB_PATH
+
+      - name: wait for VPS rebuild
+        run: |
+          rm ~/.ssh/known_hosts
+          while ! ssh -o ConnectTimeout=180 -o StrictHostKeyChecking=accept-new root@staging-ipv4.testrun.org id -u ; do sleep 1 ; done
+
+      - name: install Docker on VPS
+        run: |
+          ssh root@staging-ipv4.testrun.org 'apt-get update && apt-get install -y ca-certificates curl'
+          ssh root@staging-ipv4.testrun.org 'install -m 0755 -d /etc/apt/keyrings'
+          ssh root@staging-ipv4.testrun.org 'curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc && chmod a+r /etc/apt/keyrings/docker.asc'
+          ssh root@staging-ipv4.testrun.org 'echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian $(. /etc/os-release && echo $VERSION_CODENAME) stable" > /etc/apt/sources.list.d/docker.list'
+          ssh root@staging-ipv4.testrun.org 'apt-get update && apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin'
+
+      - name: restore ACME & DKIM state
+        run: |
+          rsync -e "ssh -o StrictHostKeyChecking=accept-new" -avz root@ns.testrun.org:/tmp/acme-ipv4/acme acme-restore || true
+          rsync -avz root@ns.testrun.org:/tmp/dkimkeys-ipv4/dkimkeys dkimkeys-restore || true
+          ssh root@staging-ipv4.testrun.org mkdir -p /srv/chatmail/dkim /srv/chatmail/certs
+          rsync -avz acme-restore/acme/ root@staging-ipv4.testrun.org:/srv/chatmail/certs/ || true
+          rsync -avz dkimkeys-restore/dkimkeys/ root@staging-ipv4.testrun.org:/srv/chatmail/dkim/ || true
+
+      - name: generate chatmail.ini with disable_ipv6
+        run: |
+          cmdeploy init staging-ipv4.testrun.org
+          sed -i 's/disable_ipv6 = False/disable_ipv6 = True/' chatmail.ini
+          sed -i 's/#\s*mtail_address/mtail_address/' chatmail.ini
+          scp chatmail.ini root@staging-ipv4.testrun.org:/srv/chatmail/chatmail.ini
+
+      - name: upload repo and deploy with Docker
+        run: |
+          GHCR_IMAGE="${{ needs.build.outputs.image }}"
+          rsync -avz --exclude='.git' --exclude='venv' --exclude='__pycache__' ./ root@staging-ipv4.testrun.org:/srv/chatmail/relay/
+          # Override: bind-mount data dirs + custom chatmail.ini + pre-built image
+          ssh root@staging-ipv4.testrun.org "cat > /srv/chatmail/relay/docker-compose.override.yaml << EOF
+          services:
+            chatmail:
+              image: ${GHCR_IMAGE}
+              volumes:
+                - /srv/chatmail/dkim:/etc/dkimkeys
+                - /srv/chatmail/certs:/var/lib/acme
+                - /srv/chatmail/chatmail.ini:/etc/chatmail/chatmail.ini
+          EOF"
+          # Login to GHCR on VPS and pull pre-built image
+          echo "${{ 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 && MAIL_DOMAIN=staging-ipv4.testrun.org docker compose up -d'
+
+      - name: wait for container to become healthy
+        run: |
+          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
+            sleep 5
+          done
+          echo "Container did not become healthy in time."
+          ssh root@staging-ipv4.testrun.org 'cd /srv/chatmail/relay && docker compose logs --tail=200'
+          exit 1
+
+      - name: run deploy-chatmail offline tests
+        run: pytest --pyargs cmdeploy
+
+      - name: set DNS entries
+        run: |
+          ssh root@staging-ipv4.testrun.org chown opendkim:opendkim -R /srv/chatmail/dkim
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail cmdeploy dns --ssh-host @local --zonefile /tmp/staging.zone --verbose'
+          ssh root@staging-ipv4.testrun.org 'docker cp chatmail:/tmp/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: cmdeploy test
+        run: CHATMAIL_DOMAIN2=ci-chatmail.testrun.org cmdeploy test --slow
+
+      - name: cmdeploy dns
+        run: |
+          ssh root@staging-ipv4.testrun.org 'docker exec chatmail cmdeploy dns -v --ssh-host @local'