Add regression test for #3

			await session.deliver(Helo("test.example.com"))

			await session.deliver(Macro(Helo.ident, {"{spam}": "no", "{ham}": "maybe"}))

			await session.deliver(EnvelopeFrom(b"test@example.com"))

	async def test_delay(self) -> None:

		"""

		Check that delays/awaits don't create race conditions

		"""

		sender = MockEditor()

		session = Session(Connect("example.com", LOCALHOST, 1025), sender)

		async def test_filter(session: Session) -> Accept:

			await trio.sleep(0.1)

			assert await session.helo() == "test.example.com"

			assert await session.envelope_from() == "test@example.com"

			return Accept()

		async with trio.open_nursery() as tg:

			tg.start_soon(test_filter, session)

			await trio.testing.wait_all_tasks_blocked()

			await session.deliver(Helo("test.example.com"))

			await session.deliver(EnvelopeFrom(b"test@example.com"))