feat: Enable OnlyFetchMvbox by default (#7190)

This is a replacement for 2260156c40 "feat: Don't fetch messages from
unknown folders", but limited to the case with `MvboxMove` enabled. It's enabled by default, so most
users still gain from not fetching messages from unknown folders.

python/tests/test_1_online.py

@@ -1776,7 +1776,7 @@ def test_group_quote(acfactory, lp):
             "xyz",
             False,
             "xyz",
-        ),  # Test that emails aren't found in a random folder
+        ),  # Test that emails are recognized in a random folder but not moved
         (
             "xyz",
             True,
@@ -1806,7 +1806,7 @@ def test_scan_folders(acfactory, lp, folder, move, expected_destination):
     ac1.stop_io()
     assert folder in ac1.direct_imap.list_folders()
 
-    lp.sec("Send a message to from ac2 to ac1 and manually move it to `folder`")
+    lp.sec("Send a message to from ac2 to ac1 and manually move it to the mvbox")
     ac1.direct_imap.select_config_folder("inbox")
     with ac1.direct_imap.idle() as idle1:
         acfactory.get_accepted_chat(ac2, ac1).send_text("hello")
@@ -1816,17 +1816,10 @@ def test_scan_folders(acfactory, lp, folder, move, expected_destination):
     lp.sec("start_io() and see if DeltaChat finds the message (" + variant + ")")
     ac1.set_config("scan_all_folders_debounce_secs", "0")
     ac1.start_io()
-    chat = ac1.create_chat(ac2)
-    n_msgs = 1  # "Messages are end-to-end encrypted."
-    if folder == "Spam":
-        msg = ac1._evtracker.wait_next_incoming_message()
-        assert msg.text == "hello"
-        n_msgs += 1
-    else:
-        ac1._evtracker.wait_idle_inbox_ready()
-    assert len(chat.get_messages()) == n_msgs
+    msg = ac1._evtracker.wait_next_incoming_message()
+    assert msg.text == "hello"
 
-    # The message has reached its destination.
+    # The message has been downloaded, which means it has reached its destination.
     ac1.direct_imap.select_folder(expected_destination)
     assert len(ac1.direct_imap.get_all_messages()) == 1
     if folder != expected_destination:

src/config.rs

@@ -165,11 +165,11 @@ pub enum Config {
     #[strum(props(default = "1"))]
     MvboxMove,
 
-    /// Watch for new messages in the "Mvbox" (aka DeltaChat folder) only.
+    /// Only watch the mvbox (aka DeltaChat folder) and, if `MvboxMove` is set, Inbox.
     ///
     /// This will not entirely disable other folders, e.g. the spam folder will also still
-    /// be watched for new messages.
-    #[strum(props(default = "0"))]
+    /// be scanned for new messages.
+    #[strum(props(default = "1"))]
     OnlyFetchMvbox,
 
     /// Whether to show classic emails or only chat messages.

src/imap.rs

@@ -823,10 +823,7 @@ impl Session {
             .context("listing folders for resync")?;
         for folder in all_folders {
             let folder_meaning = get_folder_meaning(&folder);
-            if !matches!(
-                folder_meaning,
-                FolderMeaning::Virtual | FolderMeaning::Unknown
-            ) {
+            if folder_meaning != FolderMeaning::Virtual {
                 self.resync_folder_uids(context, folder.name(), folder_meaning)
                     .await?;
             }
@@ -2044,9 +2041,9 @@ async fn spam_target_folder_cfg(
     }
 
     if needs_move_to_mvbox(context, headers).await?
-        // If OnlyFetchMvbox is set, we don't want to move the message to
-        // the inbox or sentbox where we wouldn't fetch it again:
-        || context.get_config_bool(Config::OnlyFetchMvbox).await?
+        // Don't move the message to Inbox if we won't fetch the message again there.
+        || (context.get_config_bool(Config::OnlyFetchMvbox).await?
+            && !context.get_config_bool(Config::MvboxMove).await?)
     {
         Ok(Some(Config::ConfiguredMvboxFolder))
     } else {
@@ -2573,6 +2570,9 @@ async fn should_ignore_folder(
         // Still respect the SentboxWatch setting.
         return Ok(!context.get_config_bool(Config::SentboxWatch).await?);
     }
+    if context.is_inbox(folder).await? {
+        return Ok(!context.get_config_bool(Config::MvboxMove).await?);
+    }
     Ok(!(context.is_mvbox(folder).await? || folder_meaning == FolderMeaning::Spam))
 }
 

src/imap/imap_tests.rs

@@ -122,8 +122,9 @@ async fn check_target_folder_combination(
     t.ctx
         .set_config(Config::ConfiguredSentboxFolder, Some("Sent"))
         .await?;
+    t.ctx.set_config_bool(Config::MvboxMove, mvbox_move).await?;
     t.ctx
-        .set_config(Config::MvboxMove, Some(if mvbox_move { "1" } else { "0" }))
+        .set_config_bool(Config::OnlyFetchMvbox, mvbox_move)
         .await?;
 
     if accepted_chat {

src/imap/scan_folders.rs

@@ -71,10 +71,13 @@ impl Imap {
                 _ => folder_meaning,
             };
 
-            // Don't scan folders that are watched anyway
             if !watched_folders.contains(&folder.name().to_string())
+                // Inbox shouldn't be scanned, getting messages from Inbox delayed doesn't make
+                // sense, the user should enable watching it instead.
+                && folder_meaning != FolderMeaning::Inbox
                 && folder_meaning != FolderMeaning::Trash
-                && folder_meaning != FolderMeaning::Unknown
+                && (folder_meaning != FolderMeaning::Unknown
+                    || !context.get_config_bool(Config::OnlyFetchMvbox).await?)
             {
                 self.fetch_move_delete(context, session, folder.name(), folder_meaning)
                     .await

src/sql/migrations.rs

@@ -1328,6 +1328,34 @@ CREATE INDEX gossip_timestamp_index ON gossip_timestamp (chat_id, fingerprint);
         .await?;
     }
 
+    inc_and_check(&mut migration_version, 138)?;
+    if dbversion < migration_version {
+        // `MvboxMove` now means "watch Inbox also and move chat messages from it". Preserve the old
+        // behavior for `OnlyFetchMvbox` users.
+        sql.execute_migration(
+            "INSERT OR REPLACE INTO config (keyname, value)
+             SELECT 'mvbox_move', '0'
+             FROM config WHERE keyname='only_fetch_mvbox' AND value!='0'
+            ",
+            migration_version,
+        )
+        .await?;
+    }
+
+    inc_and_check(&mut migration_version, 139)?;
+    if dbversion < migration_version {
+        // `OnlyFetchMvbox` is now 1 by default to avoid scanning unknown folders. But if the user
+        // disabled `MvboxMove`, we have to keep `OnlyFetchMvbox` unset so that Inbox is watched.
+        sql.execute_migration(
+            "INSERT OR IGNORE INTO config (keyname, value)
+             SELECT 'only_fetch_mvbox', '0'
+             FROM config WHERE keyname='mvbox_move' AND value='0'
+            ",
+            migration_version,
+        )
+        .await?;
+    }
+
     let new_version = sql
         .get_raw_config_int(VERSION_CFG)
         .await?