diff --git a/keep/api/models/alert.py b/keep/api/models/alert.py
index d6f5ac341a..21a08907f1 100644
--- a/keep/api/models/alert.py
+++ b/keep/api/models/alert.py
@@ -348,7 +348,7 @@ def from_db_instance(cls, db_alert, db_alert_to_incident):
 
 class DeleteRequestBody(BaseModel):
     fingerprint: str
-    lastReceived: str
+    lastReceived: Optional[str] = None
     restore: bool = False
 
 
diff --git a/keep/api/routes/alerts.py b/keep/api/routes/alerts.py
index bb1317f7bb..a7d54f264c 100644
--- a/keep/api/routes/alerts.py
+++ b/keep/api/routes/alerts.py
@@ -342,22 +342,32 @@ def delete_alert(
         deleted_last_received = enrichment.enrichments.get("deletedAt", [])
         assignees_last_receievd = enrichment.enrichments.get("assignees", {})
 
-    if (
-        delete_alert.restore is True
-        and delete_alert.lastReceived in deleted_last_received
-    ):
-        # Restore deleted alert
-        deleted_last_received.remove(delete_alert.lastReceived)
-    elif (
-        delete_alert.restore is False
-        and delete_alert.lastReceived not in deleted_last_received
-    ):
-        # Delete the alert if it's not already deleted (wtf basically, shouldn't happen)
-        deleted_last_received.append(delete_alert.lastReceived)
-
-    if delete_alert.lastReceived not in assignees_last_receievd:
-        # auto-assign the deleting user to the alert
-        assignees_last_receievd[delete_alert.lastReceived] = user_email
+    last_received_values = [delete_alert.lastReceived]
+    if delete_alert.lastReceived is None:
+        alerts_history = get_alerts_by_fingerprint(
+            tenant_id=tenant_id,
+            fingerprint=delete_alert.fingerprint,
+            limit=None,
+        )
+        last_received_values = [
+            alert.event["lastReceived"]
+            for alert in alerts_history
+            if alert.event.get("lastReceived")
+        ]
+
+    for last_received in last_received_values:
+        if delete_alert.restore is True and last_received in deleted_last_received:
+            # Restore deleted alert
+            deleted_last_received.remove(last_received)
+        elif (
+            delete_alert.restore is False and last_received not in deleted_last_received
+        ):
+            # Delete the alert if it's not already deleted (wtf basically, shouldn't happen)
+            deleted_last_received.append(last_received)
+
+        if last_received not in assignees_last_receievd:
+            # auto-assign the deleting user to the alert
+            assignees_last_receievd[last_received] = user_email
 
     # overwrite the enrichment
     enrichment_bl = EnrichmentsBl(tenant_id)
diff --git a/tests/test_alert_delete.py b/tests/test_alert_delete.py
new file mode 100644
index 0000000000..5f3576ae69
--- /dev/null
+++ b/tests/test_alert_delete.py
@@ -0,0 +1,60 @@
+from types import SimpleNamespace
+
+from keep.api.models.alert import DeleteRequestBody
+from keep.api.routes import alerts
+
+
+def test_delete_alert_without_last_received_deletes_all_alert_timestamps(monkeypatch):
+    captured_enrichment = {}
+    captured_fetch = {}
+
+    class FakeEnrichmentsBl:
+        def __init__(self, tenant_id):
+            assert tenant_id == "tenant-1"
+
+        def enrich_entity(self, **kwargs):
+            captured_enrichment.update(kwargs)
+
+    monkeypatch.setattr(alerts, "get_enrichment", lambda tenant_id, fingerprint: None)
+
+    def fake_get_alerts_by_fingerprint(tenant_id, fingerprint, limit=1000):
+        captured_fetch.update(
+            {
+                "tenant_id": tenant_id,
+                "fingerprint": fingerprint,
+                "limit": limit,
+            }
+        )
+        return [
+            SimpleNamespace(event={"lastReceived": "2024-01-01T00:00:00.000Z"}),
+            SimpleNamespace(event={"lastReceived": "2024-01-02T00:00:00.000Z"}),
+        ]
+
+    monkeypatch.setattr(
+        alerts, "get_alerts_by_fingerprint", fake_get_alerts_by_fingerprint
+    )
+    monkeypatch.setattr(alerts, "EnrichmentsBl", FakeEnrichmentsBl)
+
+    response = alerts.delete_alert(
+        DeleteRequestBody(fingerprint="alert-fingerprint"),
+        authenticated_entity=SimpleNamespace(
+            tenant_id="tenant-1",
+            email="user@example.com",
+        ),
+    )
+
+    assert response == {"status": "ok"}
+    assert captured_fetch == {
+        "tenant_id": "tenant-1",
+        "fingerprint": "alert-fingerprint",
+        "limit": None,
+    }
+    assert captured_enrichment["fingerprint"] == "alert-fingerprint"
+    assert captured_enrichment["enrichments"]["deletedAt"] == [
+        "2024-01-01T00:00:00.000Z",
+        "2024-01-02T00:00:00.000Z",
+    ]
+    assert captured_enrichment["enrichments"]["assignees"] == {
+        "2024-01-01T00:00:00.000Z": "user@example.com",
+        "2024-01-02T00:00:00.000Z": "user@example.com",
+    }