diff --git a/backend/app/main.py b/backend/app/main.py
index 1ab8841..23d7e98 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -30,6 +30,37 @@ settings = get_settings()
 inbound_server = InboundSMTPServer()
 
 
+async def ensure_mongo_index(collection, keys, **options) -> None:
+    """Create an index, replacing any same-name or same-key index with different options."""
+    key_list = [(field, direction) for field, direction in keys]
+    options = dict(options)
+    name = options.get("name")
+    if not name:
+        name = "_".join(f"{field}_{direction}" for field, direction in key_list)
+        options["name"] = name
+
+    desired_unique = bool(options.get("unique"))
+    desired_sparse = bool(options.get("sparse"))
+
+    async for index in collection.list_indexes():
+        if index["name"] == "_id_":
+            continue
+        index_key = list(index["key"].items())
+        same_key = index_key == key_list
+        same_name = index["name"] == name
+        if not same_key and not same_name:
+            continue
+        same_options = (
+            bool(index.get("unique")) == desired_unique
+            and bool(index.get("sparse")) == desired_sparse
+        )
+        if same_key and same_name and same_options:
+            return
+        await collection.drop_index(index["name"])
+
+    await collection.create_index(keys, **options)
+
+
 async def backfill_missing_thread_ids(database) -> None:
     cursor = database.mailbox_entries.find({"thread_id": None})
     async for entry in cursor:
@@ -141,24 +172,28 @@ async def lifespan(_: FastAPI):
     async with SessionFactory() as session:
         await ensure_platform_domain(session)
         await session.commit()
-    await mongo_db.emails.create_index([("recipients", 1), ("created_at", -1)])
-    await mongo_db.emails.create_index([("cc", 1), ("created_at", -1)])
-    await mongo_db.emails.create_index([("bcc", 1), ("created_at", -1)])
-    await mongo_db.emails.create_index([("sender", 1), ("created_at", -1)])
-    await mongo_db.emails.create_index([("account_id", 1), ("created_at", -1)])
-    await mongo_db.messages.create_index(
+    await ensure_mongo_index(mongo_db.emails, [("recipients", 1), ("created_at", -1)])
+    await ensure_mongo_index(mongo_db.emails, [("cc", 1), ("created_at", -1)])
+    await ensure_mongo_index(mongo_db.emails, [("bcc", 1), ("created_at", -1)])
+    await ensure_mongo_index(mongo_db.emails, [("sender", 1), ("created_at", -1)])
+    await ensure_mongo_index(mongo_db.emails, [("account_id", 1), ("created_at", -1)])
+    await ensure_mongo_index(
+        mongo_db.messages,
         [("delivery_key", 1)],
         unique=True,
         sparse=True,
     )
-    await mongo_db.message_tombstones.create_index(
+    await ensure_mongo_index(
+        mongo_db.message_tombstones,
         [("delivery_key", 1)],
         unique=True,
     )
-    await mongo_db.messages.create_index(
-        [("subject", "text"), ("snippet", "text"), ("sender.name", "text")]
+    await ensure_mongo_index(
+        mongo_db.messages,
+        [("subject", "text"), ("snippet", "text"), ("sender.name", "text")],
     )
-    await mongo_db.mailbox_entries.create_index(
+    await ensure_mongo_index(
+        mongo_db.mailbox_entries,
         [
             ("account_id", 1),
             ("mailbox", 1),
@@ -166,22 +201,27 @@ async def lifespan(_: FastAPI):
             ("deletion_state", 1),
             ("created_at", -1),
             ("_id", -1),
-        ]
+        ],
     )
-    await mongo_db.mailbox_entries.create_index(
-        [("account_id", 1), ("is_read", 1), ("created_at", -1), ("_id", -1)]
+    await ensure_mongo_index(
+        mongo_db.mailbox_entries,
+        [("account_id", 1), ("is_read", 1), ("created_at", -1), ("_id", -1)],
     )
-    await mongo_db.mailbox_entries.create_index(
+    await ensure_mongo_index(
+        mongo_db.mailbox_entries,
         [("account_id", 1), ("message_id", 1), ("mailbox", 1)],
         unique=True,
     )
-    await mongo_db.mailbox_entries.create_index(
-        [("account_id", 1), ("is_starred", 1), ("created_at", -1), ("_id", -1)]
+    await ensure_mongo_index(
+        mongo_db.mailbox_entries,
+        [("account_id", 1), ("is_starred", 1), ("created_at", -1), ("_id", -1)],
     )
-    await mongo_db.sticky_notes.create_index(
-        [("account_id", 1), ("updated_at", -1)]
+    await ensure_mongo_index(
+        mongo_db.sticky_notes,
+        [("account_id", 1), ("updated_at", -1)],
     )
-    await mongo_db.mailbox_entries.create_index(
+    await ensure_mongo_index(
+        mongo_db.mailbox_entries,
         [
             ("account_id", 1),
             ("sender.name", "text"),
@@ -191,37 +231,37 @@ async def lifespan(_: FastAPI):
         ],
         name="mailbox_search",
     )
-    await mongo_db.messages.create_index(
-        [("message_id", 1)],
-        sparse=True,
-    )
-    await mongo_db.messages.create_index(
-        [("message_id_folded", 1)],
-        sparse=True,
-    )
-    await mongo_db.messages.create_index(
+    await ensure_mongo_index(mongo_db.messages, [("message_id", 1)], sparse=True)
+    await ensure_mongo_index(mongo_db.messages, [("message_id_folded", 1)], sparse=True)
+    await ensure_mongo_index(
+        mongo_db.messages,
         [("generated_from_handoff_message_id", 1)],
         sparse=True,
         unique=True,
     )
-    await mongo_db.messages.create_index(
+    await ensure_mongo_index(
+        mongo_db.messages,
         [("mirrored_from_external_message_id", 1)],
         sparse=True,
         unique=True,
     )
-    await mongo_db.messages.create_index(
+    await ensure_mongo_index(
+        mongo_db.messages,
         [("handoff_delivery_key", 1)],
         sparse=True,
         unique=True,
     )
-    await mongo_db.mailbox_entries.create_index(
-        [("account_id", 1), ("thread_id", 1), ("event_at", -1), ("_id", -1)]
+    await ensure_mongo_index(
+        mongo_db.mailbox_entries,
+        [("account_id", 1), ("thread_id", 1), ("event_at", -1), ("_id", -1)],
     )
-    await mongo_db.email_threads.create_index(
-        [("account_id", 1), ("last_message_at", -1), ("_id", -1)]
+    await ensure_mongo_index(
+        mongo_db.email_threads,
+        [("account_id", 1), ("last_message_at", -1), ("_id", -1)],
     )
-    await mongo_db.human_handoff_rules.create_index(
-        [("account_id", 1), ("updated_at", -1)]
+    await ensure_mongo_index(
+        mongo_db.human_handoff_rules,
+        [("account_id", 1), ("updated_at", -1)],
     )
     account_ids = await mongo_db.human_handoff_rules.distinct("account_id")
     for account_id in account_ids:
@@ -236,45 +276,56 @@ async def lifespan(_: FastAPI):
                     {"_id": rule["_id"]},
                     {"$set": {"priority": index}},
                 )
-    await mongo_db.human_handoff_rules.create_index(
+    await ensure_mongo_index(
+        mongo_db.human_handoff_rules,
         [("account_id", 1), ("priority", 1)],
         unique=True,
     )
-    await mongo_db.human_handoff_rules.create_index(
+    await ensure_mongo_index(
+        mongo_db.human_handoff_rules,
         [("account_id", 1), ("name_key", 1)],
         unique=True,
         sparse=True,
     )
-    await mongo_db.human_handoffs.create_index(
-        [("account_id", 1), ("updated_at", -1)]
+    await ensure_mongo_index(
+        mongo_db.human_handoffs,
+        [("account_id", 1), ("updated_at", -1)],
     )
-    await mongo_db.human_handoffs.create_index(
+    await ensure_mongo_index(
+        mongo_db.human_handoffs,
         [("account_id", 1), ("external_thread_id", 1)],
         unique=True,
     )
-    await mongo_db.human_handoffs.create_index(
+    await ensure_mongo_index(
+        mongo_db.human_handoffs,
         [("account_id", 1), ("handoff_thread_id", 1)],
         unique=True,
     )
-    await mongo_db.handoff_message_links.create_index(
-        [("handoff_id", 1), ("created_at", -1)]
+    await ensure_mongo_index(
+        mongo_db.handoff_message_links,
+        [("handoff_id", 1), ("created_at", -1)],
     )
-    await mongo_db.handoff_message_links.create_index(
+    await ensure_mongo_index(
+        mongo_db.handoff_message_links,
         [("handoff_id", 1), ("source_message_id", 1), ("relationship", 1)],
         unique=True,
         sparse=True,
     )
-    await mongo_db.handoff_delivery_jobs.create_index(
+    await ensure_mongo_index(
+        mongo_db.handoff_delivery_jobs,
         [("idempotency_key", 1)],
         unique=True,
     )
-    await mongo_db.handoff_delivery_jobs.create_index(
-        [("status", 1), ("next_attempt_at", 1), ("created_at", 1)]
+    await ensure_mongo_index(
+        mongo_db.handoff_delivery_jobs,
+        [("status", 1), ("next_attempt_at", 1), ("created_at", 1)],
     )
-    await mongo_db.mailbox_entries.create_index(
-        [("account_id", 1), ("message_scope", 1), ("mailbox", 1), ("event_at", -1)]
+    await ensure_mongo_index(
+        mongo_db.mailbox_entries,
+        [("account_id", 1), ("message_scope", 1), ("mailbox", 1), ("event_at", -1)],
     )
-    await mongo_db.messages.create_index(
+    await ensure_mongo_index(
+        mongo_db.messages,
         [("message_id", 1), ("message_scope", 1)],
         sparse=True,
     )