diff --git a/bugsnag/delivery.py b/bugsnag/delivery.py
index acd2da2..6dc8cd0 100644
--- a/bugsnag/delivery.py
+++ b/bugsnag/delivery.py
@@ -93,7 +93,6 @@ def deliver_sessions(self, config, payload: Any, options=None):
                 options = {}
 
             options['endpoint'] = config.session_endpoint
-            options['success'] = 202
 
             self.deliver(config, payload, options)
 
@@ -151,10 +150,14 @@ def request():
             status = resp.getcode()
 
             if 'success' in options:
-                success = options['success']
+                # if an expected status code has been given then it must match
+                # exactly with the actual status code
+                success = status == options['success']
             else:
-                success = 200
-            if status != success:
+                # warn if we don't get a 2xx status code by default
+                success = status >= 200 and status < 300
+
+            if not success:
                 config.logger.warning(
                     'Delivery to %s failed, status %d' % (uri, status)
                 )
@@ -184,12 +187,16 @@ def request():
 
             response = requests.post(uri, **req_options)
             status = response.status_code
+
             if 'success' in options:
-                success = options['success']
+                # if an expected status code has been given then it must match
+                # exactly with the actual status code
+                success = status == options['success']
             else:
-                success = requests.codes.ok
+                # warn if we don't get a 2xx status code by default
+                success = status >= 200 and status < 300
 
-            if status != success:
+            if not success:
                 config.logger.warning(
                     'Delivery to %s failed, status %d' % (uri, status)
                 )
diff --git a/tests/test_delivery.py b/tests/test_delivery.py
index 591bcfd..d86a6a5 100644
--- a/tests/test_delivery.py
+++ b/tests/test_delivery.py
@@ -1,9 +1,12 @@
 import pytest
 import warnings
 import sys
+import logging
+from unittest.mock import Mock
 
 from bugsnag import Configuration
 from bugsnag.delivery import (
+    Delivery,
     UrllibDelivery,
     RequestsDelivery,
     create_default_delivery,
@@ -66,6 +69,71 @@ def test_misconfigured_sessions_endpoint_sends_warning(self):
             self.assertEqual(1, len(warn))
             self.assertEqual(0, len(self.server.events_received))
 
+    def test_does_not_warn_on_200_status_code(self):
+        delivery = Mock(wraps=create_default_delivery())
+        logger = Mock(spec=logging.Logger)
+
+        self.config.configure(delivery=delivery, logger=logger)
+
+        self.server.respond_to_next_request_with(200)
+
+        delivery.deliver(self.config, '{"apiKey":"aaab"}')
+
+        assert logger.warning.call_count == 0
+        assert len(self.server.events_received) == 1
+
+    def test_does_not_warn_on_202_status_code(self):
+        delivery = Mock(wraps=create_default_delivery())
+        logger = Mock(spec=logging.Logger)
+
+        self.config.configure(delivery=delivery, logger=logger)
+
+        self.server.respond_to_next_request_with(202)
+
+        delivery.deliver(self.config, '{"apiKey":"aaab"}')
+
+        print(logger.warning.assert_not_called())
+        assert logger.warning.call_count == 0
+        assert len(self.server.events_received) == 1
+
+    def test_warns_on_400_status_code_for_events(self):
+        delivery = Mock(wraps=create_default_delivery())
+        logger = Mock(spec=logging.Logger)
+
+        self.config.configure(delivery=delivery, logger=logger)
+
+        self.server.respond_to_next_request_with(300)
+
+        delivery.deliver(self.config, '{"apiKey":"aaab"}')
+
+        expected = 'Delivery to %s failed, status %d' % (
+            self.config.endpoint,
+            300
+        )
+
+        logger.warning.assert_called_once_with(expected)
+
+        assert len(self.server.events_received) == 1
+
+    def test_warns_on_300_status_code_for_sessions(self):
+        delivery = Mock(wraps=create_default_delivery())
+        logger = Mock(spec=logging.Logger)
+
+        self.config.configure(delivery=delivery, logger=logger)
+
+        self.server.respond_to_next_request_with(300)
+
+        delivery.deliver_sessions(self.config, '{"apiKey":"aaab"}')
+
+        expected = 'Delivery to %s failed, status %d' % (
+            self.config.session_endpoint,
+            300
+        )
+
+        logger.warning.assert_called_once_with(expected)
+
+        assert len(self.server.sessions_received) == 1
+
     def test_it_calls_post_delivery_callback(self):
         callback_was_called = False
 
diff --git a/tests/utils.py b/tests/utils.py
index d17e138..38009bf 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -81,6 +81,7 @@ def __init__(self, wait_for_duplicate_requests: bool):
         self.sessions_received = []
         self.paused = False
         self.wait_for_duplicate_requests = wait_for_duplicate_requests
+        self._response_codes = []
 
         class Handler(SimpleHTTPRequestHandler):
             def do_POST(handler):
@@ -114,7 +115,12 @@ def do_POST(handler):
                         'unknown endpoint requested: ' + handler.path
                     )
 
-                handler.send_response(200)
+                try:
+                    code = self._response_codes.pop()
+                except IndexError:
+                    code = 200
+
+                handler.send_response(code)
                 handler.end_headers()
 
                 return ()
@@ -175,6 +181,9 @@ def sent_report_count(self) -> int:
     def sent_session_count(self) -> int:
         return len(self.sessions_received)
 
+    def respond_to_next_request_with(self, status_code: int) -> None:
+        self._response_codes.append(status_code)
+
 
 class ScaryException(Exception):
     class NestedScaryException(Exception):