diff --git a/app/dao/returned_letters_dao.py b/app/dao/returned_letters_dao.py
index e69de29bb..24d8ae438 100644
--- a/app/dao/returned_letters_dao.py
+++ b/app/dao/returned_letters_dao.py
@@ -0,0 +1,40 @@
+from datetime import datetime
+
+from sqlalchemy.dialects.postgresql import insert
+
+from app import db
+from app.dao.dao_utils import transactional
+from app.models import Notification, NotificationHistory, ReturnedLetter
+
+
+@transactional
+def insert_or_update_returned_letters(references):
+    data = _get_notification_ids_for_references(references)
+    now = datetime.utcnow()
+    for row in data:
+        table = ReturnedLetter.__table__
+
+        stmt = insert(table).values(
+            reported_at=now,
+            service_id=row.service_id,
+            notification_id=row.id)
+
+        stmt = stmt.on_conflict_do_update(
+            index_elements=[table.c.notification_id],
+            set_={
+                'reported_at': now,
+            }
+        )
+        db.session.connection().execute(stmt)
+
+
+def _get_notification_ids_for_references(references):
+    notification_ids = db.session.query(Notification.id, Notification.service_id).filter(
+        Notification.reference.in_(references)
+    ).all()
+
+    notification_history_ids = db.session.query(NotificationHistory.id, NotificationHistory.service_id).filter(
+        NotificationHistory.reference.in_(references)
+    ).all()
+
+    return notification_ids + notification_history_ids
diff --git a/tests/app/dao/test_returned_letters_dao.py b/tests/app/dao/test_returned_letters_dao.py
index e69de29bb..1a94f1fde 100644
--- a/tests/app/dao/test_returned_letters_dao.py
+++ b/tests/app/dao/test_returned_letters_dao.py
@@ -0,0 +1,83 @@
+from datetime import datetime
+
+from freezegun import freeze_time
+
+from app.dao.returned_letters_dao import insert_or_update_returned_letters
+from app.models import ReturnedLetter
+from tests.app.db import create_notification, create_notification_history
+
+
+def test_insert_or_update_returned_letters_inserts(sample_letter_template):
+    notification = create_notification(template=sample_letter_template,
+                                       reference='ref1')
+    history = create_notification_history(template=sample_letter_template,
+                                          reference='ref2')
+
+    assert ReturnedLetter.query.count() == 0
+
+    insert_or_update_returned_letters(['ref1', 'ref2'])
+
+    returned_letters = ReturnedLetter.query.all()
+
+    assert len(returned_letters) == 2
+    returned_letters_ = [x.notification_id for x in returned_letters]
+    assert notification.id in returned_letters_
+    assert history.id in returned_letters_
+
+
+def test_insert_or_update_returned_letters_updates(sample_letter_template):
+    notification = create_notification(template=sample_letter_template,
+                                       reference='ref1')
+    history = create_notification_history(template=sample_letter_template,
+                                          reference='ref2')
+
+    assert ReturnedLetter.query.count() == 0
+    with freeze_time('2019-12-09 13:30'):
+        insert_or_update_returned_letters(['ref1', 'ref2'])
+        returned_letters = ReturnedLetter.query.all()
+        assert len(returned_letters) == 2
+        for x in returned_letters:
+            assert x.reported_at == datetime(2019, 12, 9, 13, 30)
+            assert x.notification_id in [notification.id, history.id]
+
+    with freeze_time('2019-12-10 14:20'):
+        insert_or_update_returned_letters(['ref1', 'ref2'])
+
+        returned_letters = ReturnedLetter.query.all()
+        assert len(returned_letters) == 2
+        for x in returned_letters:
+            assert x.reported_at == datetime(2019, 12, 10, 14, 20)
+            assert x.notification_id in [notification.id, history.id]
+
+
+def test_insert_or_update_returned_letters_when_no_notification(sample_letter_template):
+    insert_or_update_returned_letters(['ref1'])
+    assert ReturnedLetter.query.count() == 0
+
+
+def test_insert_or_update_returned_letters_for_history_only(sample_letter_template):
+    history_1 = create_notification_history(template=sample_letter_template,
+                                            reference='ref1')
+    history_2 = create_notification_history(template=sample_letter_template,
+                                            reference='ref2')
+
+    assert ReturnedLetter.query.count() == 0
+    insert_or_update_returned_letters(['ref1', 'ref2'])
+    returned_letters = ReturnedLetter.query.all()
+    assert len(returned_letters) == 2
+    for x in returned_letters:
+        assert x.notification_id in [history_1.id, history_2.id]
+
+
+def test_insert_or_update_returned_letters_with_duplicates_in_reference_list(sample_letter_template):
+    notification_1 = create_notification(template=sample_letter_template,
+                                         reference='ref1')
+    notification_2 = create_notification(template=sample_letter_template,
+                                         reference='ref2')
+
+    assert ReturnedLetter.query.count() == 0
+    insert_or_update_returned_letters(['ref1', 'ref2', 'ref1', 'ref2'])
+    returned_letters = ReturnedLetter.query.all()
+    assert len(returned_letters) == 2
+    for x in returned_letters:
+        assert x.notification_id in [notification_1.id, notification_2.id]