diff --git a/app/main/views/send.py b/app/main/views/send.py
index 5940c37be..6ea79fca3 100644
--- a/app/main/views/send.py
+++ b/app/main/views/send.py
@@ -476,7 +476,7 @@ def send_test_preview(service_id, template_id, filetype):
     return TemplatePreview.from_utils_template(template, filetype, page=request.args.get('page'))
 
 
-def _check_messages(service_id, template_id, upload_id, preview_row, letters_as_pdf=False):
+def _check_messages(service_id, template_id, upload_id, preview_row, letters_as_pdf=False, write_metadata=False):
 
     try:
         # The happy path is that the job doesn’t already exist, so the
@@ -561,7 +561,7 @@ def _check_messages(service_id, template_id, upload_id, preview_row, letters_as_
     elif preview_row > 2:
         abort(404)
 
-    if any(recipients) and not recipients.has_errors:
+    if any(recipients) and not recipients.has_errors and write_metadata:
         set_metadata_on_csv_upload(
             service_id,
             upload_id,
@@ -604,7 +604,7 @@ def _check_messages(service_id, template_id, upload_id, preview_row, letters_as_
 @user_has_permissions('send_messages', restrict_admin_usage=True)
 def check_messages(service_id, template_id, upload_id, row_index=2):
 
-    data = _check_messages(service_id, template_id, upload_id, row_index)
+    data = _check_messages(service_id, template_id, upload_id, row_index, write_metadata=True)
 
     if (
         data['recipients'].too_many_rows or
@@ -642,7 +642,7 @@ def check_messages_preview(service_id, template_id, upload_id, filetype, row_ind
         abort(404)
 
     template = _check_messages(
-        service_id, template_id, upload_id, row_index, letters_as_pdf=True
+        service_id, template_id, upload_id, row_index, letters_as_pdf=True, write_metadata=False,
     )['template']
     return TemplatePreview.from_utils_template(template, filetype)
 
diff --git a/tests/app/main/views/test_send.py b/tests/app/main/views/test_send.py
index 83d1fcccc..2300beaf6 100644
--- a/tests/app/main/views/test_send.py
+++ b/tests/app/main/views/test_send.py
@@ -666,6 +666,39 @@ def test_upload_valid_csv_shows_preview_and_table(
             assert normalize_spaces(str(row.select('td')[index + 1])) == cell
 
 
+def test_upload_valid_csv_only_sets_meta_if_filename_known(
+    client_request,
+    mocker,
+    mock_get_live_service,
+    mock_get_service_letter_template,
+    mock_get_users_by_service,
+    mock_get_service_statistics,
+    mock_get_job_doesnt_exist,
+    mock_s3_set_metadata,
+    fake_uuid,
+):
+
+    mocker.patch('app.main.views.send.s3download', return_value="""
+        addressline1, addressline2, postcode
+        House       , 1 Street    , SW1A 1AA
+    """)
+    mocker.patch(
+        'app.main.views.send.TemplatePreview.from_utils_template',
+        return_value='foo'
+    )
+
+    client_request.get(
+        'main.check_messages_preview',
+        service_id=SERVICE_ONE_ID,
+        template_id=fake_uuid,
+        upload_id=fake_uuid,
+        filetype='pdf',
+        _test_page_title=False,
+    )
+
+    assert len(mock_s3_set_metadata.call_args_list) == 0
+
+
 def test_file_name_truncated_to_fit_in_s3_metadata(
     client_request,
     mocker,