restore environment-based queue names

tests/test_queue.py

@@ -1,5 +1,5 @@
 import pytest
-from atst.queue import queue, send_mail
+from atst.queue import queue
 
 # ensure queue is always empty for unit testing
 @pytest.fixture(scope="function", autouse=True)
@@ -11,7 +11,7 @@ def reset_queue():
 
 def test_send_mail():
     initial = len(queue.get_queue())
-    send_mail.queue(
+    queue.send_mail(
         ["lordvader@geocities.net"], "death start", "how is it coming along?"
     )
     assert len(queue.get_queue()) == initial + 1