do imap expiration/deletion after fetching messages, to avoid unneccessary delays.

CHANGELOG.md

@@ -12,6 +12,7 @@
 - Further improve finding the correct server after logging in #3208
 - `get_connectivity_html()` returns HTML as non-scalable #3213
 - add update-serial to `DC_EVENT_WEBXDC_STATUS_UPDATE` #3215
+- Speed up message receiving via IMAP a bit #3225
 
 
 ## 1.77.0

src/scheduler.rs

@@ -168,6 +168,13 @@ async fn fetch_idle(ctx: &Context, connection: &mut Imap, folder: Config) -> Int
                 return connection.fake_idle(ctx, Some(watch_folder)).await;
             }
 
+            // Fetch the watched folder.
+            if let Err(err) = connection.fetch_move_delete(ctx, &watch_folder).await {
+                connection.trigger_reconnect(ctx).await;
+                warn!(ctx, "{:#}", err);
+                return InterruptInfo::new(false);
+            }
+
             // Mark expired messages for deletion.
             if let Err(err) = delete_expired_imap_messages(ctx)
                 .await
@@ -176,13 +183,6 @@ async fn fetch_idle(ctx: &Context, connection: &mut Imap, folder: Config) -> Int
                 warn!(ctx, "{:#}", err);
             }
 
-            // Fetch the watched folder.
-            if let Err(err) = connection.fetch_move_delete(ctx, &watch_folder).await {
-                connection.trigger_reconnect(ctx).await;
-                warn!(ctx, "{:#}", err);
-                return InterruptInfo::new(false);
-            }
-
             // Scan additional folders only after finishing fetching the watched folder.
             //
             // On iOS the application has strictly limited time to work in background, so we may not