diff --git a/migrations.py b/migrations.py
index 6461d57..a968549 100644
--- a/migrations.py
+++ b/migrations.py
@@ -277,3 +277,8 @@ async def m012_chat_schedules_seen_and_notification_jobs(db):
         );
         """
     )
+
+
+async def m013_persistent_notifications(db):
+    await db.execute("ALTER TABLE chat.categories ADD COLUMN persistent_notifications BOOLEAN NOT NULL DEFAULT FALSE;")
+    await db.execute("ALTER TABLE chat.chats ADD COLUMN last_admin_notification_at TIMESTAMP;")
diff --git a/models.py b/models.py
index 8646bcc..907235f 100644
--- a/models.py
+++ b/models.py
@@ -18,6 +18,7 @@ class CreateCategories(BaseModel):
     claim_split: float | None = 0
     guest_notifications: bool | None = False
     public_note: str | None = DEFAULT_PUBLIC_NOTE
+    persistent_notifications: bool = False
     notify_telegram: str | None = None
     notify_nostr: str | None = None
     notify_email: str | None = None
@@ -46,6 +47,7 @@ class Categories(BaseModel):
     claim_split: float | None = 0
     guest_notifications: bool | None = False
     public_note: str | None = DEFAULT_PUBLIC_NOTE
+    persistent_notifications: bool = False
     notify_telegram: str | None = None
     notify_nostr: str | None = None
     notify_email: str | None = None
@@ -152,6 +154,7 @@ class ChatSession(BaseModel):
     participants: list[dict] = Field(default_factory=list)
     messages: list[dict] = Field(default_factory=list)
     last_message_at: datetime | None = None
+    last_admin_notification_at: datetime | None = None
 
     created_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
     updated_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
diff --git a/services.py b/services.py
index f139c28..08dc95e 100644
--- a/services.py
+++ b/services.py
@@ -289,6 +289,7 @@ async def _notify_new_chat(
         message,
         "chat.new",
     )
+    chat.last_admin_notification_at = datetime.now(timezone.utc)
 
 
 async def _notify_chat_reply(
@@ -566,7 +567,41 @@ def _sanitize_public_chat(chat: ChatSession) -> ChatSession:
     return sanitized
 
 
-async def _append_message(chat: ChatSession, message: ChatMessage, unread: bool) -> ChatSession:
+async def _notify_persistent_message(chat: ChatSession, message: ChatMessage) -> None:
+    if message.sender_role != "public" or message.message_type != "message" or chat.resolved:
+        return
+    previous = [m for m in chat.messages if m.get("message_type", "message") == "message"]
+    if not previous or previous[0].get("sender_id") != message.sender_id:
+        return
+    if any(m.get("sender_role") == "admin" for m in previous):
+        return
+    category = await get_categories_by_id(chat.categories_id)
+    if not category or not category.persistent_notifications:
+        return
+    if not (category.notify_telegram or category.notify_nostr or category.notify_email):
+        return
+    last_notification = chat.last_admin_notification_at
+    if last_notification is None:
+        last_notification = datetime.fromisoformat(previous[0]["created_at"])
+    if last_notification.tzinfo is None:
+        last_notification = last_notification.replace(tzinfo=timezone.utc)
+    if message.created_at - last_notification < timedelta(minutes=15):
+        return
+    await send_notification(
+        category.notify_telegram,
+        [category.notify_nostr] if category.notify_nostr else [],
+        _parse_notify_emails(category.notify_email),
+        f'Unanswered chat: "{message.message}" {_build_chat_link(None, chat)}',
+        "chat.reminder",
+    )
+    chat.last_admin_notification_at = message.created_at
+
+
+async def _append_message(
+    chat: ChatSession, message: ChatMessage, unread: bool, notify_persistent: bool = True
+) -> ChatSession:
+    if notify_persistent:
+        await _notify_persistent_message(chat, message)
     payload = _serialize_message(message)
     chat.messages.append(payload)
     chat.last_message_at = message.created_at
@@ -614,7 +649,7 @@ async def _handle_lnurlp_drawdown(
     )
     if not chat.messages and not after_hours:
         await _notify_new_chat(category, chat, base_url, data.message)
-    await _append_message(chat, message, unread=True)
+    await _append_message(chat, message, unread=True, notify_persistent=not after_hours)
     if after_hours:
         await _notify_after_hours_admin(category, chat, message, base_url)
     else:
@@ -689,7 +724,7 @@ async def _send_free_message(
     )
     if not chat.messages and not after_hours:
         await _notify_new_chat(category, chat, base_url, data.message)
-    await _append_message(chat, message, unread=True)
+    await _append_message(chat, message, unread=True, notify_persistent=not after_hours)
     if after_hours:
         await _notify_after_hours_admin(category, chat, message, base_url)
     elif data.sender_role == "public" and not user_id:
diff --git a/static/index.js b/static/index.js
index 1c003b4..f231524 100644
--- a/static/index.js
+++ b/static/index.js
@@ -17,6 +17,7 @@ window.PageChat = {
           denomination: 'sat',
           claim_split: 0,
           guest_notifications: false,
+          persistent_notifications: false,
           public_note:
             'we aim to reply as soon as possible but it may take up to 24hrs for a reply',
           notify_telegram: null,
@@ -262,6 +263,7 @@ window.PageChat = {
         denomination: 'sat',
         claim_split: 0,
         guest_notifications: false,
+        persistent_notifications: false,
         public_note:
           'we aim to reply as soon as possible but it may take up to 24hrs for a reply',
         notify_telegram: null,
diff --git a/static/index.vue b/static/index.vue
index 3318b41..895b5cc 100644
--- a/static/index.vue
+++ b/static/index.vue
@@ -544,6 +544,23 @@
             label="Email address (comma separated)"
             hint="Optional notification target"
           ></q-input>
+          <q-toggle
+            v-if="
+              categoriesFormDialog.data.notify_telegram ||
+              categoriesFormDialog.data.notify_nostr ||
+              categoriesFormDialog.data.notify_email
+            "
+            v-model="categoriesFormDialog.data.persistent_notifications"
+            label="Persistent notifications"
+            color="primary"
+          ></q-toggle>
+          <div
+            v-if="categoriesFormDialog.data.persistent_notifications"
+            class="text-caption text-grey"
+          >
+            Notify again when the chat starter sends another message at least 15
+            minutes after the last notification, until support replies.
+          </div>
         </q-expansion-item>
 
         <q-expansion-item
diff --git a/tests/test_persistent_notifications.py b/tests/test_persistent_notifications.py
new file mode 100644
index 0000000..b208b31
--- /dev/null
+++ b/tests/test_persistent_notifications.py
@@ -0,0 +1,90 @@
+from datetime import datetime, timedelta, timezone
+from unittest.mock import AsyncMock
+from uuid import uuid4
+
+import pytest
+
+from chat.crud import (  # type: ignore[import]
+    create_categories,
+    create_chat,
+    get_categories_by_id,
+    get_chat,
+)
+from chat.models import ChatMessage, ChatSession, CreateCategories  # type: ignore[import]
+from chat.services import _append_message  # type: ignore[import]
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "enabled,elapsed,replied,sender,message_type,resolved,expected",
+    [
+        (True, 899, False, "guest", "message", False, 0),
+        (True, 900, False, "guest", "message", False, 1),
+        (True, 1800, False, "guest", "message", False, 1),
+        (False, 1800, False, "guest", "message", False, 0),
+        (True, 1800, True, "guest", "message", False, 0),
+        (True, 1800, False, "other", "message", False, 0),
+        (True, 1800, False, "guest", "tip", False, 0),
+        (True, 1800, False, "guest", "message", True, 0),
+    ],
+)
+async def test_persistent_notification(
+    monkeypatch, enabled, elapsed, replied, sender, message_type, resolved, expected
+):
+    notify = AsyncMock()
+    monkeypatch.setattr("chat.services.send_notification", notify)
+    monkeypatch.setattr("chat.services._broadcast_chat", AsyncMock())
+    category = await create_categories(
+        uuid4().hex,
+        CreateCategories(name="Support", persistent_notifications=enabled, notify_email="support@example.com"),
+    )
+    saved_category = await get_categories_by_id(category.id)
+    assert saved_category.persistent_notifications == enabled
+    now = datetime.now(timezone.utc)
+    initial = now - timedelta(seconds=elapsed)
+    messages = [
+        {
+            "id": "first",
+            "sender_id": "guest",
+            "sender_role": "public",
+            "message": "Hello",
+            "created_at": initial.isoformat(),
+        }
+    ]
+    if replied:
+        messages.append({"id": "reply", "sender_id": "support", "sender_role": "admin", "message": "Hi"})
+    chat = ChatSession(
+        id=uuid4().hex,
+        categories_id=category.id,
+        messages=messages,
+        last_admin_notification_at=initial,
+        resolved=resolved,
+    )
+    await create_chat(category.id, chat)
+    message = ChatMessage(
+        id=uuid4().hex,
+        sender_id=sender,
+        sender_name=sender,
+        sender_role="public",
+        message="Anyone there?",
+        message_type=message_type,
+        created_at=now,
+    )
+    await _append_message(chat, message, unread=True)
+    assert notify.await_count == expected
+    saved = await get_chat(chat.id)
+    assert saved is not None
+    if expected:
+        assert abs((saved.last_admin_notification_at.replace(tzinfo=timezone.utc) - now).total_seconds()) < 1
+        assert notify.call_args.args[2] == ["support@example.com"]
+        assert "Anyone there?" in notify.call_args.args[3]
+        # A further message inside the cooldown must not send another reminder,
+        # including after loading the chat back from the database.
+        message.id = uuid4().hex
+        message.created_at = now + timedelta(minutes=1)
+        await _append_message(saved, message, unread=True)
+        assert notify.await_count == 1
+        message.id = uuid4().hex
+        message.created_at = now + timedelta(minutes=15)
+        await _append_message(saved, message, unread=True)
+        assert notify.await_count == 2