diff --git a/mail4one/smtp.py b/mail4one/smtp.py
index a1e516b..1b1f4de 100644
--- a/mail4one/smtp.py
+++ b/mail4one/smtp.py
@@ -36,7 +36,8 @@ class MyHandler(AsyncMessage):
     async def handle_message(self, m: Message):  # type: ignore[override]
         all_mboxes: set[str] = set()
         for addr in self.rcpt_tos:
-            all_mboxes.union(self.mbox_finder(addr))
+            for mbox in self.mbox_finder(addr):
+                all_mboxes.add(mbox)
         if not all_mboxes:
             return
         for mbox in all_mboxes:
@@ -49,7 +50,7 @@ class MyHandler(AsyncMessage):
                 gen = BytesGenerator(fp, policy=email.policy.SMTP)
                 gen.flatten(m)
             for mbox in all_mboxes:
-                shutil.copy(temp_email_path, self.mails_path / mbox / 'new')
+                shutil.copy2(temp_email_path, self.mails_path / mbox / 'new')
 
 
 def protocol_factory_starttls(mails_path: Path,
@@ -92,13 +93,13 @@ async def create_smtp_server_starttls(host: str,
                                     start_serving=False)
 
 
-async def create_smtp_server_tls(dirpath: Path,
-                                 mbox_finder: Callable[[str], [str]],
+async def create_smtp_server_tls(host: str,
                                  port: int,
-                                 host="",
+                                 mails_path: Path,
+                                 mbox_finder: Callable[[str], [str]],
                                  context: ssl.SSLContext | None = None):
     loop = asyncio.get_event_loop()
-    return await loop.create_server(partial(protocol_factory, dirpath),
+    return await loop.create_server(partial(protocol_factory, mails_path, mbox_finder),
                                     host=host,
                                     port=port,
                                     ssl=context,
diff --git a/mail4one/smtp_test.py b/mail4one/smtp_test.py
new file mode 100644
index 0000000..b48012c
--- /dev/null
+++ b/mail4one/smtp_test.py
@@ -0,0 +1,76 @@
+import asyncio
+import logging
+import unittest
+import smtplib
+import tempfile
+import os
+
+from pathlib import Path
+
+from .smtp import create_smtp_server_tls
+
+TEST_MBOX = 'foobar_mails'
+MAILS_PATH: Path
+
+
+def setUpModule() -> None:
+    global MAILS_PATH
+    logging.basicConfig(level=logging.CRITICAL)
+    td = tempfile.TemporaryDirectory(prefix="m41.smtp.")
+    unittest.addModuleCleanup(td.cleanup)
+    MAILS_PATH = Path(td.name)
+    os.mkdir(MAILS_PATH / TEST_MBOX)
+    for md in ('new', 'cur', 'tmp'):
+        os.mkdir(MAILS_PATH / TEST_MBOX / md)
+
+
+class TestSMTP(unittest.IsolatedAsyncioTestCase):
+
+    async def asyncSetUp(self) -> None:
+        logging.basicConfig(level=logging.DEBUG)
+        smtp_server = await create_smtp_server_tls(
+            host="127.0.0.1",
+            port=7996,
+            mails_path=MAILS_PATH,
+            mbox_finder=lambda addr: [TEST_MBOX])
+        self.task = asyncio.create_task(smtp_server.serve_forever())
+
+    async def test_send_mail(self) -> None:
+        msg = b"""From: foo@sender.com
+        To: "foo@bar.com"
+
+        Hello world
+        Byee
+        """
+        msg = b"".join(l.strip() + b"\r\n" for l in msg.splitlines())
+        local_port: str
+
+        def send_mail():
+            nonlocal local_port
+            server = smtplib.SMTP(host="127.0.0.1", port=7996)
+            server.sendmail("foo@sender.com", "foo@bar.com", msg)
+            _, local_port = server.sock.getsockname()
+            server.close()
+
+        await asyncio.to_thread(send_mail)
+        expected = f"""From: foo@sender.com
+        To: "foo@bar.com"
+        X-Peer: ('127.0.0.1', {local_port})
+        X-MailFrom: foo@sender.com
+        X-RcptTo: foo@bar.com
+
+        Hello world
+        Byee
+        """
+        expected = "".join(l.strip() + "\r\n" for l in expected.splitlines())
+        mails = list((MAILS_PATH / TEST_MBOX / 'new').glob("*"))
+        self.assertEqual(len(mails), 1)
+        self.assertEqual(mails[0].read_bytes(), expected.encode())
+
+    async def asyncTearDown(self) -> None:
+        logging.debug("at teardown")
+        self.task.cancel("test done")
+
+
+if __name__ == "__main__":
+    unittest.main()