diff --git a/apps/base/mail/kustomization.yaml b/apps/base/mail/kustomization.yaml
index bdeda69..21224c2 100644
--- a/apps/base/mail/kustomization.yaml
+++ b/apps/base/mail/kustomization.yaml
@@ -14,8 +14,17 @@ resources:
   - stalwart-configmap.yaml
   - stalwart-pdb.yaml
   - stalwart-service.yaml
+  - stalwart-sieve-reconcile-cronjob.yaml
   - stalwart-statefulset.yaml
   - valkey.yaml
   - vaultauth.yaml
   - vaultstaticsecret.yaml
   - vmpodscrape.yaml
+
+configMapGenerator:
+  - name: stalwart-sieve-reconcile
+    namespace: mail
+    options:
+      disableNameSuffixHash: true
+    files:
+      - sieve-reconcile.py=resources/sieve-reconcile.py
diff --git a/apps/base/mail/resources/sieve-reconcile.py b/apps/base/mail/resources/sieve-reconcile.py
new file mode 100644
index 0000000..ce76fcb
--- /dev/null
+++ b/apps/base/mail/resources/sieve-reconcile.py
@@ -0,0 +1,99 @@
+import base64
+import json
+import os
+import re
+import sys
+import urllib.parse
+import urllib.request
+
+URL = os.environ["STALWART_URL"].rstrip("/")
+AUTH = "Basic " + base64.b64encode(
+    f"{os.environ['STALWART_USER']}:{os.environ['STALWART_PASSWORD']}".encode()
+).decode()
+USING = ["urn:ietf:params:jmap:core", "urn:ietf:params:jmap:sieve", "urn:stalwart:jmap"]
+HEADER = 'require ["include"];\ninclude :global "spam-to-junk";\n'
+HAS_INCLUDE = re.compile(r'\binclude\b[^;]*"spam-to-junk"')
+REQUIRE = re.compile(r"\s*require\b")
+
+
+def http(path, data=None, ctype="application/json"):
+    req = urllib.request.Request(URL + path, data=data, headers={"Authorization": AUTH})
+    if data is not None:
+        req.add_header("Content-Type", ctype)
+    with urllib.request.urlopen(req, timeout=30) as resp:
+        return resp.read()
+
+
+def jmap(*calls):
+    body = json.dumps({"using": USING, "methodCalls": [[m, a, str(i)] for i, (m, a) in enumerate(calls)]})
+    responses = json.loads(http("/jmap", body.encode()))["methodResponses"]
+    for name, args, _ in responses:
+        if name == "error":
+            raise RuntimeError(args)
+    return [args for _, args, _ in responses]
+
+
+def with_include(script):
+    lines = script.splitlines(keepends=True)
+    i, in_require = 0, False
+    while i < len(lines):
+        line = lines[i].strip()
+        if in_require or REQUIRE.match(lines[i]):
+            in_require = not line.endswith(";")
+        elif line and not line.startswith("#"):
+            break
+        i += 1
+    return HEADER + "".join(lines[:i]) + "".join(lines[i:])
+
+
+def users():
+    ids, position = [], 0
+    while True:
+        (page,) = jmap(("x:Account/query", {"position": position, "limit": 500}))
+        ids += page["ids"]
+        position += len(page["ids"])
+        if not page["ids"] or position >= page.get("total", position):
+            break
+    for start in range(0, len(ids), 500):
+        (got,) = jmap(("x:Account/get", {"ids": ids[start:start + 500], "properties": ["@type", "name"]}))
+        yield from (a for a in got["list"] if a["@type"] == "User")
+
+
+def reconcile(account):
+    acct = account["id"]
+    (got,) = jmap(("SieveScript/get", {"accountId": acct}))
+    scripts = got["list"]
+    target = next((s for s in scripts if s["isActive"]), None) or next(
+        (s for s in scripts if s["name"] == "default"), None
+    )
+    content = ""
+    if target:
+        content = http(f"/jmap/download/{acct}/{target['blobId']}/script").decode()
+        if target["isActive"] and HAS_INCLUDE.search(content):
+            return
+    if not HAS_INCLUDE.search(content):
+        content = with_include(content)
+    blob = json.loads(http(f"/jmap/upload/{acct}/", content.encode(), "application/sieve"))["blobId"]
+    if target:
+        args = {"accountId": acct, "update": {target["id"]: {"blobId": blob}},
+                "onSuccessActivateScript": target["id"]}
+        action = f"added spam-to-junk include to {target['name']!r}"
+    else:
+        args = {"accountId": acct, "create": {"d": {"name": "default", "blobId": blob}},
+                "onSuccessActivateScript": "#d"}
+        action = "created and activated 'default'"
+    (res,) = jmap(("SieveScript/set", args))
+    failed = res.get("notCreated") or res.get("notUpdated")
+    if failed:
+        raise RuntimeError(failed)
+    print(f"{account['name']}: {action}", flush=True)
+
+
+errors = 0
+for account in users():
+    try:
+        reconcile(account)
+    except Exception as err:
+        errors += 1
+        print(f"{account['name']}: {err}", file=sys.stderr, flush=True)
+sys.exit(1 if errors else 0)
diff --git a/apps/base/mail/stalwart-sieve-reconcile-cronjob.yaml b/apps/base/mail/stalwart-sieve-reconcile-cronjob.yaml
new file mode 100644
index 0000000..ac2f154
--- /dev/null
+++ b/apps/base/mail/stalwart-sieve-reconcile-cronjob.yaml
@@ -0,0 +1,70 @@
+---
+# Keeps an active personal Sieve script including the global spam-to-junk
+# script on every individual account, so rspamd-tagged mail lands in Junk.
+apiVersion: batch/v1
+kind: CronJob
+metadata:
+  name: stalwart-sieve-reconcile
+  namespace: mail
+spec:
+  schedule: "*/15 * * * *"
+  concurrencyPolicy: Forbid
+  successfulJobsHistoryLimit: 3
+  failedJobsHistoryLimit: 3
+  jobTemplate:
+    spec:
+      activeDeadlineSeconds: 600
+      backoffLimit: 1
+      template:
+        metadata:
+          labels:
+            app.kubernetes.io/name: stalwart-sieve-reconcile
+        spec:
+          restartPolicy: Never
+          automountServiceAccountToken: false
+          securityContext:
+            runAsNonRoot: true
+            runAsUser: 65532
+            runAsGroup: 65532
+            seccompProfile:
+              type: RuntimeDefault
+          containers:
+            - name: reconcile
+              image: docker.io/library/python:3.13-alpine
+              command:
+                - python
+                - /scripts/sieve-reconcile.py
+              env:
+                - name: STALWART_URL
+                  value: http://stalwart.mail.svc:8080
+                - name: STALWART_USER
+                  valueFrom:
+                    secretKeyRef:
+                      name: stalwart-admin
+                      key: username
+                - name: STALWART_PASSWORD
+                  valueFrom:
+                    secretKeyRef:
+                      name: stalwart-admin
+                      key: password
+              securityContext:
+                allowPrivilegeEscalation: false
+                readOnlyRootFilesystem: true
+                capabilities:
+                  drop:
+                    - ALL
+              resources:
+                limits:
+                  cpu: 200m
+                  memory: 128Mi
+                requests:
+                  cpu: 50m
+                  memory: 64Mi
+              volumeMounts:
+                - name: scripts
+                  mountPath: /scripts
+                  readOnly: true
+          volumes:
+            - name: scripts
+              configMap:
+                name: stalwart-sieve-reconcile