diff --git a/mailing/mailing.py b/mailing/mailing.py
index 6b6fc45..5d9884c 100644
--- a/mailing/mailing.py
+++ b/mailing/mailing.py
@@ -41,9 +41,9 @@ def send_sendgrid_email(self, **kwargs: Any) -> Any | None:
         )
         try:
             response = sg.send(message)
-            return response
         except Exception as e:
             if hasattr(e, "body"):
                 logger.error("SendGrid error body: %s", e.body)
             logger.exception("SendGrid exception")
             return None
+        return response
diff --git a/tests/__init__.py b/mailing/tests/__init__.py
similarity index 100%
rename from tests/__init__.py
rename to mailing/tests/__init__.py
diff --git a/mailing/tests/conftest.py b/mailing/tests/conftest.py
new file mode 100644
index 0000000..124002d
--- /dev/null
+++ b/mailing/tests/conftest.py
@@ -0,0 +1,79 @@
+import os
+import types
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def _env_settings(monkeypatch):
+    """Ensure settings has required env vars for tests and patch settings module.
+    Autouse so all tests get consistent defaults.
+    """
+    monkeypatch.setenv("SENDGRID_API_KEY", "test-api-key")
+    monkeypatch.setenv("SENDGRID_FROM_EMAIL", "from@example.com")
+
+    # Also patch the already-imported settings module so defaults apply even if
+    # settings was imported before this fixture ran.
+    import settings as _settings
+
+    monkeypatch.setattr(_settings, "SENDGRID_API_KEY", "test-api-key", raising=False)
+    monkeypatch.setattr(_settings, "SENDGRID_FROM_EMAIL", "from@example.com", raising=False)
+    yield
+
+
+@pytest.fixture()
+def email_data():
+    return {
+        "subject": "Hello",
+        "message": "Plain text body",
+        "recipient_list": ["to1@example.com", "to2@example.com"],
+        "from_email": "from@example.com",
+        "html_content": "<p>HTML</p>",
+    }
+
+
+class DummyMail:
+    """Lightweight substitute for sendgrid.helpers.mail.Mail used in tests."""
+
+    def __init__(self, **kwargs):
+        # store all kwargs to allow assertions in tests
+        self.kwargs = kwargs
+
+
+class DummySendGridClient:
+    """A dummy client whose send() we can customize per test."""
+
+    def __init__(self, *_, **__):
+        # send behavior can be overridden by tests via attribute replacement
+        self._response = "ok"
+
+    def send(self, mail):  # noqa: D401
+        """Return a predefined response; overridden in tests for error path."""
+        return self._response
+
+
+@pytest.fixture()
+def mock_sendgrid_success(monkeypatch):
+    """Patch mailing.mailing with dummy Mail and SendGrid client that succeed."""
+    import mailing.mailing as mm
+
+    monkeypatch.setattr(mm, "Mail", DummyMail, raising=True)
+    monkeypatch.setattr(mm, "SendGridAPIClient", DummySendGridClient, raising=True)
+    return mm
+
+
+@pytest.fixture()
+def mock_sendgrid_error(monkeypatch):
+    """Patch mailing.mailing with dummy Mail and a client that raises Exception."""
+    import mailing.mailing as mm
+
+    class ErroringClient(DummySendGridClient):
+        def send(self, mail):
+            # Simulate an exception that has a body attribute like SendGridError
+            err = Exception("send failed")
+            # attach a body attribute to mimic SDK errors
+            err.body = {"errors": ["some error"]}
+            raise err
+
+    monkeypatch.setattr(mm, "Mail", DummyMail, raising=True)
+    monkeypatch.setattr(mm, "SendGridAPIClient", ErroringClient, raising=True)
+    return mm
diff --git a/mailing/tests/test_sendgrid.py b/mailing/tests/test_sendgrid.py
new file mode 100644
index 0000000..7375334
--- /dev/null
+++ b/mailing/tests/test_sendgrid.py
@@ -0,0 +1,89 @@
+import logging
+
+from mailing.mailing import Email
+
+
+class TestSendgridMailing:
+    def test_send_sendgrid_email_success_returns_response(self, mock_sendgrid_success, email_data):
+        # Given
+        email = Email(**email_data)
+
+        # When
+        response = email.send_sendgrid_email()
+
+        # Then
+        assert response == "ok"
+
+        # Also verify Mail was constructed with expected kwargs
+        # The DummyMail stores kwargs; access the last constructed instance by recreating with same data
+        # Instead, we build another to compare keys; more robust is to rebuild and compare content
+        m = mock_sendgrid_success.Mail(
+            from_email=email_data["from_email"],
+            to_emails=email_data["recipient_list"],
+            subject=email_data["subject"],
+            html_content=email_data["html_content"],
+            plain_text_content=email_data["message"],
+        )
+        # ensure keys are as expected; values are validated via equality
+        expected = m.kwargs
+
+        # Now recreate the Email and intercept the actual Mail instance to assert args
+        captured = {}
+
+        class CapturingMail(mock_sendgrid_success.Mail):
+            def __init__(self, **kwargs):
+                super().__init__(**kwargs)
+                captured.update(kwargs)
+
+        # Patch in the capturing version
+        import mailing.mailing as mm
+
+        mm.Mail = CapturingMail
+        Email(**email_data).send_sendgrid_email()
+
+        assert captured == expected
+
+    def test_send_sendgrid_email_uses_default_from_email_when_not_provided(
+        self, mock_sendgrid_success
+    ):
+        # Given: no from_email passed, should use settings.SENDGRID_FROM_EMAIL from env
+        data = {
+            "subject": "Subj",
+            "message": "Body",
+            "recipient_list": ["t@example.com"],
+            "html_content": None,
+        }
+        # Capture constructed kwargs
+        captured = {}
+
+        class CapturingMail(mock_sendgrid_success.Mail):
+            def __init__(self, **kwargs):
+                super().__init__(**kwargs)
+                captured.update(kwargs)
+
+        import mailing.mailing as mm
+
+        mm.Mail = CapturingMail
+
+        # When
+        Email(**data).send_sendgrid_email()
+
+        # Then
+        assert captured["from_email"] == "from@example.com"
+        assert captured["plain_text_content"] == "Body"
+        assert captured["html_content"] is None
+
+    def test_send_sendgrid_email_logs_and_returns_none_on_exception(
+        self, mock_sendgrid_error, caplog, email_data
+    ):
+        # Given
+        email = Email(**email_data)
+
+        # When
+        with caplog.at_level(logging.ERROR):
+            result = email.send_sendgrid_email()
+
+        # Then
+        assert result is None
+        # Ensure an error was logged containing our simulated body
+        assert any("SendGrid error body" in rec.getMessage() for rec in caplog.records)
diff --git a/tests/test_dummy.py b/tests/test_dummy.py
deleted file mode 100644
index f4f5361..0000000
--- a/tests/test_dummy.py
+++ /dev/null
@@ -1,2 +0,0 @@
-def test_dummy():
-    assert True