Copy directly-sent e-mails to an IMAP Sent folder, with a live folder picker

A raw SMTP send has no server-side "Sent" copy on its own (unlike IMAP
drafts, which are inherently server-side) -- add an opt-in checkbox plus a
configurable target folder so directly sent Mahnungen/SEPA-info-mails still
show up in the account's Gesendet/Sent folder like a normal mail client
would leave them. Applies only to "send" delivery; drafts already live on
the server by definition.

Both the Entwürfe- and Gesendet-folder fields are now editable comboboxes:
a new "Ordnerliste laden" button fetches the real folder list from the IMAP
server (needs working credentials first) via LIST, decoding folder names
from modified UTF-7 (RFC 3501) so names like "Entwürfe" render correctly
instead of as "Entw&APw-rfe". Free text still works -- ensure_imap_folder()
creates the folder on first use if it doesn't exist yet, checked once per
batch rather than before every single message.

mail_delivery.append_to_imap_drafts() became the more general
append_message(client, content, folder=, flags=), reused for both the
\Draft and \Seen cases.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/test_mail_delivery.py

@@ -33,6 +33,7 @@ class _FakeSmtpClient:
 
 class _FakeImapClient:
     instances: list["_FakeImapClient"] = []
+    default_list_result: tuple = ("OK", [])
     error = Exception
 
     def __init__(self, host, port, **kwargs):
@@ -43,6 +44,11 @@ class _FakeImapClient:
         self.login_args: tuple | None = None
         self.appended: list[tuple] = []
         self.append_result = ("OK", [b"APPEND completed"])
+        self.selected: list[str] = []
+        self.select_result = ("OK", [b"1"])
+        self.created: list[str] = []
+        self.create_result = ("OK", [b"CREATE completed"])
+        self.list_result = _FakeImapClient.default_list_result
         _FakeImapClient.instances.append(self)
 
     def starttls(self, *args, **kwargs):
@@ -57,6 +63,20 @@ class _FakeImapClient:
         self.calls.append("append")
         return self.append_result
 
+    def select(self, folder, readonly=False):
+        self.selected.append(folder)
+        self.calls.append("select")
+        return self.select_result
+
+    def create(self, folder):
+        self.created.append(folder)
+        self.calls.append("create")
+        return self.create_result
+
+    def list(self):
+        self.calls.append("list")
+        return self.list_result
+
     def logout(self):
         self.calls.append("logout")
 
@@ -65,6 +85,7 @@ class _FakeImapClient:
 def _reset_fakes():
     _FakeSmtpClient.instances.clear()
     _FakeImapClient.instances.clear()
+    _FakeImapClient.default_list_result = ("OK", [])
     yield
 
 
@@ -118,23 +139,85 @@ def test_send_via_smtp_logs_in_and_sends_reusing_one_connection(monkeypatch) ->
     assert len(fake.sent_messages) == 2
 
 
-def test_append_to_imap_drafts_uses_configured_folder(monkeypatch) -> None:
+def test_append_message_uses_configured_folder_and_flags(monkeypatch) -> None:
     _patch_imap(monkeypatch)
     with mail_delivery.imap_session(IMAP_SETTINGS) as client:
-        mail_delivery.append_to_imap_drafts(client, MESSAGE, folder="INBOX.Entwürfe")
+        mail_delivery.append_message(client, MESSAGE, folder="INBOX.Entwürfe", flags=r"(\Draft)")
 
     fake = _FakeImapClient.instances[0]
     assert fake.login_args == ("board@example.org", "secret")
-    assert fake.appended == [("INBOX.Entwürfe", r"(\Draft)", None, MESSAGE)]
+    # The folder name travels the wire in modified UTF-7, not raw UTF-8.
+    assert fake.appended == [("INBOX.Entw&APw-rfe", r"(\Draft)", None, MESSAGE)]
     assert fake.calls == ["login", "append", "logout"]
 
 
-def test_append_to_imap_drafts_raises_on_rejected_status(monkeypatch) -> None:
+def test_append_message_raises_on_rejected_status(monkeypatch) -> None:
     _patch_imap(monkeypatch)
     with mail_delivery.imap_session(IMAP_SETTINGS) as client:
         client.append_result = ("NO", [b"Mailbox does not exist"])
         with pytest.raises(RepositoryError, match="Mailbox does not exist"):
-            mail_delivery.append_to_imap_drafts(client, MESSAGE, folder="Missing")
+            mail_delivery.append_message(client, MESSAGE, folder="Missing", flags=r"(\Seen)")
+
+
+def test_ensure_imap_folder_skips_creation_when_folder_already_exists(monkeypatch) -> None:
+    _patch_imap(monkeypatch)
+    with mail_delivery.imap_session(IMAP_SETTINGS) as client:
+        mail_delivery.ensure_imap_folder(client, "INBOX.Sent")
+
+    fake = _FakeImapClient.instances[0]
+    assert fake.selected == ["INBOX.Sent"]
+    assert fake.created == []
+
+
+def test_ensure_imap_folder_creates_missing_folder(monkeypatch) -> None:
+    _patch_imap(monkeypatch)
+    with mail_delivery.imap_session(IMAP_SETTINGS) as client:
+        client.select_result = ("NO", [b"Mailbox does not exist"])
+        mail_delivery.ensure_imap_folder(client, "Archiv.Neu")
+
+    fake = _FakeImapClient.instances[0]
+    assert fake.selected == ["Archiv.Neu"]
+    assert fake.created == ["Archiv.Neu"]
+
+
+def test_ensure_imap_folder_raises_when_creation_fails(monkeypatch) -> None:
+    _patch_imap(monkeypatch)
+    with mail_delivery.imap_session(IMAP_SETTINGS) as client:
+        client.select_result = ("NO", [b"no such mailbox"])
+        client.create_result = ("NO", [b"Permission denied"])
+        with pytest.raises(RepositoryError, match="Permission denied"):
+            mail_delivery.ensure_imap_folder(client, "Verboten")
+
+
+@pytest.mark.parametrize(
+    ("plain", "wire"),
+    [
+        ("INBOX", "INBOX"),
+        ("Entwürfe", "Entw&APw-rfe"),
+        ("INBOX.Entwürfe", "INBOX.Entw&APw-rfe"),
+        ("Test & Foo", "Test &- Foo"),
+    ],
+)
+def test_imap_utf7_round_trips(plain, wire) -> None:
+    assert mail_delivery._encode_imap_utf7(plain) == wire
+    assert mail_delivery._decode_imap_utf7(wire) == plain
+
+
+def test_list_imap_folders_parses_and_decodes_list_response(monkeypatch) -> None:
+    _patch_imap(monkeypatch)
+    _FakeImapClient.default_list_result = (
+        "OK",
+        [
+            rb'(\HasNoChildren) "." INBOX',
+            rb'(\HasNoChildren) "." INBOX.Entw&APw-rfe',
+            rb'(\HasNoChildren) "." "INBOX.Gesendete Objekte"',
+        ],
+    )
+
+    folders = mail_delivery.list_imap_folders(IMAP_SETTINGS)
+
+    assert folders == ["INBOX", "INBOX.Entwürfe", "INBOX.Gesendete Objekte"]
+    assert _FakeImapClient.instances[0].calls == ["login", "list", "logout"]
 
 
 def test_smtp_session_wraps_connection_errors(monkeypatch) -> None: