(feature): move expired mail to trash and keep trash by days

CHANGELOG.md

@@ -6,6 +6,19 @@ The format follows [Keep a Changelog](https://keepachangelog.com/) and [Semantic
 
 ## [Unreleased]
 
+## [0.3.2] - 2026-09-19
+
+Expired folder mail goes to Trash; Trash can be kept forever or purged after a number of days.
+
+### Changed
+
+- **Settings → Retention…**: folder days (`0` = keep forever) now **move** older messages to Trash after Get Messages, instead of deleting them permanently. The Trash row uses the same days field: `0` keeps Trash forever, a number of days **permanently deletes** old Trash. The grid shows the action per row.
+- Delete (toolbar, **Del**, empty folder, delete rules) moves messages to Trash. If Trash is missing, it is created. Deleting from Trash is still permanent. Local stores honor Trash when emptying a folder.
+
+### Fixed
+
+- Local folder stores no longer skip Trash when emptying a folder (messages go to **Deleted Items**).
+
 ## [0.3.1] - 2026-09-19
 
 ### Fixed

README.md

@@ -167,7 +167,7 @@ IMAP **QUOTA** from the gestore (when the server supports it) is a thin bar on t
 | New store | File menu: empty bucket (`Inbox`, `Drafts`, `Sent Items`, `Deleted Items`) with `postclient.store.json` and `mail.db`. |
 | Attach store | File menu: pick a folder that already has `postclient.store.json`. Recovers mail + search after an AppData wipe. |
 | Move / Detach store | Copy the whole directory (or unregister it). The folder stays on disk when detached. |
-| Retention | **Settings → Retention…**: days per folder (`0` = forever). Older messages are deleted permanently after Get Messages. |
+| Retention | **Settings → Retention…**: days per folder (`0` = forever). Expired folder mail is moved to Trash after Get Messages. On Trash, `0` keeps it forever and a number of days permanently deletes older Trash. |
 | Rules | **Settings → Rules**: **Import rules…** reads this app’s JSON export or a legacy `.rwz` file. **Export rules…** writes JSON. Each rule is bound to an **account**; a move folder can live on another mailbox (including a store). They run on Get Messages, on import, and from **Run all rules**. |
 | Print | Readable HTML of the (optionally unwrapped) message |
 | Save PDF | Same content as a PDF |

data/eu.postclient.desktop.metainfo.xml

@@ -30,6 +30,11 @@
     <display_length compare="ge">768</display_length>
   </requires>
   <releases>
+    <release version="0.3.2" date="2026-09-19">
+      <description>
+        <p>Retention moves expired folder mail to Trash. Trash can be kept forever or purged after a number of days. Delete sends messages to Trash.</p>
+      </description>
+    </release>
     <release version="0.3.1" date="2026-09-19">
       <description>
         <p>The main window opens on launch from the Windows setup. Closing the window exits the app.</p>

src/Directory.Build.props

@@ -3,7 +3,7 @@
     <LangVersion>latest</LangVersion>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
-    <Version>0.3.1</Version>
+    <Version>0.3.2</Version>
     <Product>Postclient</Product>
     <AssemblyTitle>Postclient</AssemblyTitle>
     <Authors>Maksym Sadovnychyy</Authors>

src/MaksIT.PostClient.Client/LocalMailImport.cs

@@ -145,7 +145,7 @@ public sealed class LocalMailImport {
       if (!MailRuleEngine.Matches(rule, from, to, subject, text, hasAttachment))
         continue;
       if (rule.Action == MailRuleAction.Delete)
-        folder = MailRuleEngine.ResolveFolder("Trash", catalog) ?? "Trash";
+        folder = MailRetention.ResolveTrash(catalog);
       else if (rule.Action == MailRuleAction.Move)
         folder = MailRuleEngine.ExactFolder(rule.Folder, catalog) ?? folder;
       if (rule.Action == MailRuleAction.MarkRead)

src/MaksIT.PostClient.Client/LocalStoreSession.cs

@@ -247,12 +247,21 @@ public sealed class LocalStoreSession : IMailSession, IFileMailStore {
     string? trashFolder,
     CancellationToken cancellationToken = default) =>
     _io.RunAsync(() => {
-      _ = trashFolder;
       var dir = FolderDir(folder);
       if (!Directory.Exists(dir))
         return Task.FromResult(Result.Ok());
-      foreach (var file in Directory.EnumerateFiles(dir, "*.eml")) {
+      var files = Directory.EnumerateFiles(dir, "*.eml").ToList();
+      var toTrash = !string.IsNullOrWhiteSpace(trashFolder)
+        && !folder.Equals(trashFolder, StringComparison.OrdinalIgnoreCase);
+      if (toTrash)
+        Directory.CreateDirectory(FolderDir(trashFolder!));
+      foreach (var file in files) {
         cancellationToken.ThrowIfCancellationRequested();
+        if (toTrash) {
+          var dest = MessagePath(trashFolder!, NextUid(trashFolder!));
+          File.Copy(file, dest, overwrite: false);
+        }
+
         File.Delete(file);
       }
 

src/MaksIT.PostClient.Client/MailWorkerHost.cs

@@ -112,29 +112,89 @@ public sealed class MailWorkerHost : IDisposable {
     var count = 0;
     var configuration = _files.Current;
     configuration.EnsureDefaults();
-    foreach (var rule in configuration.Retention) {
+    foreach (var job in MailRetention.Jobs(configuration.Retention)) {
-      if (rule.Days <= 0 || string.IsNullOrWhiteSpace(rule.MailboxId) || string.IsNullOrWhiteSpace(rule.Folder))
+      var known = _archive.ListFolders(job.MailboxId);
+      var folder = MailRetention.BindFolder(job.Folder, known);
+      if (string.IsNullOrWhiteSpace(folder))
         continue;
-      var cutoff = DateTimeOffset.UtcNow.AddDays(-rule.Days);
+      var cutoff = DateTimeOffset.UtcNow.AddDays(-job.Days);
-      var ids = _archive.UidsOlderThan(rule.MailboxId, rule.Folder, cutoff);
+      var ids = _archive.UidsOlderThan(job.MailboxId, folder, cutoff);
       if (ids.Count == 0)
         continue;
-      var paths = _archive.RemoveUids(rule.MailboxId, rule.Folder, ids);
+      if (MailRetention.IsTrash(folder)) {
-      foreach (var path in paths) {
+        DeleteFiles(_archive.RemoveUids(job.MailboxId, folder, ids));
-        try {
+        count += ids.Count;
-          if (File.Exists(path))
+        continue;
-            File.Delete(path);
-        }
-        catch {
-        }
       }
 
-      count += ids.Count;
+      var trash = MailRetention.ResolveTrash(known);
+      if (folder.Equals(trash, StringComparison.OrdinalIgnoreCase)) {
+        DeleteFiles(_archive.RemoveUids(job.MailboxId, folder, ids));
+        count += ids.Count;
+        continue;
+      }
+
+      count += MoveToTrash(configuration, job.MailboxId, folder, trash, ids);
     }
 
     return Ok(count.ToString());
   }
 
+  private int MoveToTrash(
+    Configuration configuration,
+    string mailboxId,
+    string folder,
+    string trash,
+    IReadOnlyList<uint> ids) {
+    var moved = new List<uint>();
+    foreach (var uid in ids) {
+      try {
+        var source = _archive.EmlPath(mailboxId, folder, uid);
+        var destUid = _archive.NextUid(mailboxId, trash);
+        var dest = RetentionDestPath(configuration, mailboxId, trash, destUid);
+        if (!string.IsNullOrWhiteSpace(source)
+            && File.Exists(source)
+            && !source.Equals(dest, StringComparison.OrdinalIgnoreCase)) {
+          var dir = Path.GetDirectoryName(dest);
+          if (!string.IsNullOrWhiteSpace(dir))
+            Directory.CreateDirectory(dir);
+          File.Copy(source, dest, overwrite: false);
+        }
+
+        _archive.CopyIndexed(mailboxId, folder, uid, mailboxId, trash, dest, destUid);
+        moved.Add(uid);
+      }
+      catch {
+      }
+    }
+
+    if (moved.Count > 0)
+      DeleteFiles(_archive.RemoveUids(mailboxId, folder, moved));
+    return moved.Count;
+  }
+
+  private static string RetentionDestPath(
+    Configuration configuration,
+    string mailboxId,
+    string folder,
+    uint uid) {
+    var box = configuration.FindMailbox(mailboxId);
+    if (box is not null)
+      return MailArchiveLayout.EmlPath(box, configuration.Mailboxes, folder, uid);
+    return ArchiveFiles.EmlPath(mailboxId, folder, uid);
+  }
+
+  private static void DeleteFiles(IEnumerable<string> paths) {
+    foreach (var path in paths) {
+      try {
+        if (!string.IsNullOrWhiteSpace(path) && File.Exists(path))
+          File.Delete(path);
+      }
+      catch {
+      }
+    }
+  }
+
   public void Dispose() =>
     _semantic?.Dispose();
 

src/MaksIT.PostClient.Shared/Configuration.cs

@@ -68,6 +68,12 @@ public sealed class Configuration {
     Semantic ??= new SemanticSearchSettings();
     Semantic.Normalize();
     Rules ??= [];
+    foreach (var rule in Rules) {
+      rule.MailboxId ??= "";
+      rule.FolderMailboxId ??= "";
+      rule.Folder ??= "";
+    }
+
     Retention ??= [];
     foreach (var row in Retention) {
       row.MailboxId ??= "";

src/MaksIT.PostClient.Shared/MailRetention.cs

@@ -0,0 +1,68 @@
+namespace MaksIT.PostClient.Shared;
+
+
+public static class MailRetention {
+  public const string TrashFolder = "Deleted Items";
+
+  public static bool IsTrash(string? name, string? fullName = null) =>
+    MailFolderRole.Kind(name, fullName ?? name) == "trash";
+
+  public static string ResolveTrash(IEnumerable<string>? folders) {
+    foreach (var folder in folders ?? []) {
+      if (string.IsNullOrWhiteSpace(folder))
+        continue;
+      if (IsTrash(folder))
+        return folder;
+    }
+
+    return TrashFolder;
+  }
+
+  public static string ResolveTrash(IReadOnlyList<(string Name, string FullName)> folders) {
+    foreach (var folder in folders) {
+      if (string.IsNullOrWhiteSpace(folder.FullName))
+        continue;
+      if (MailFolderRole.Kind(folder.Name, folder.FullName) == "trash")
+        return folder.FullName;
+    }
+
+    return TrashFolder;
+  }
+
+  public static string BindFolder(string? wanted, IEnumerable<string>? folders) {
+    var list = (folders ?? [])
+      .Where(folder => !string.IsNullOrWhiteSpace(folder))
+      .Select(folder => (folder, folder))
+      .ToList();
+    return MailRuleEngine.ExactFolder(wanted, list) ?? (wanted ?? "").Trim();
+  }
+
+  public static IReadOnlyList<FolderRetention> Jobs(IEnumerable<FolderRetention>? retention) {
+    var map = new Dictionary<string, FolderRetention>(StringComparer.OrdinalIgnoreCase);
+    foreach (var row in retention ?? [])
+      Put(map, row);
+    return map.Values.Where(row => row.Days > 0).ToList();
+  }
+
+  private static void Put(Dictionary<string, FolderRetention> map, FolderRetention row) {
+    if (string.IsNullOrWhiteSpace(row.MailboxId) || string.IsNullOrWhiteSpace(row.Folder))
+      return;
+    var mailboxId = row.MailboxId.Trim();
+    var folder = row.Folder.Trim();
+    var days = Math.Max(0, row.Days);
+    if (days <= 0)
+      return;
+    var key = mailboxId + "\n" + folder;
+    if (map.TryGetValue(key, out var existing)) {
+      if (days < existing.Days)
+        existing.Days = days;
+      return;
+    }
+
+    map[key] = new FolderRetention {
+      MailboxId = mailboxId,
+      Folder = folder,
+      Days = days
+    };
+  }
+}

src/MaksIT.PostClient.Shared/UiCopy.cs

@@ -118,6 +118,12 @@ public sealed partial class UiCopy {
 
   public string RetentionDays { get; init; } = "";
 
+  public string RetentionAction { get; init; } = "";
+
+  public string RetentionToTrash { get; init; } = "";
+
+  public string RetentionPurge { get; init; } = "";
+
   public string RetentionRun { get; init; } = "";
 
   public string LocalStore { get; init; } = "";
@@ -616,8 +622,11 @@ public sealed partial class UiCopy {
       DetachStoreDone = "Detached {0}. The folder is still on disk.",
       MoveStoreDone = "Moved store {0}.",
       Retention = "_Retention…",
-      RetentionHint = "Per folder. 0 keeps mail forever. A number of days permanently deletes older messages (not Trash).",
+      RetentionHint = "Per folder. 0 keeps mail forever. Folder days move older messages to Trash. Trash days permanently delete, or 0 to keep Trash forever.",
       RetentionDays = "Days",
+      RetentionAction = "When expired",
+      RetentionToTrash = "Move to Trash",
+      RetentionPurge = "Delete permanently",
       RetentionRun = "Run now",
       LocalStore = "Local store",
       LocalStoreAppData = "App data (default)",
@@ -880,8 +889,11 @@ public sealed partial class UiCopy {
       DetachStoreDone = "Sganciato {0}. La cartella resta sul disco.",
       MoveStoreDone = "Spostato l’archivio {0}.",
       Retention = "_Conservazione…",
-      RetentionHint = "Per cartella. 0 conserva per sempre. Un numero di giorni elimina in modo permanente i messaggi più vecchi (non nel Cestino).",
+      RetentionHint = "Per cartella. 0 conserva per sempre. I giorni della cartella spostano i messaggi più vecchi nel Cestino. I giorni del Cestino eliminano in modo permanente, oppure 0 per tenere il Cestino per sempre.",
       RetentionDays = "Giorni",
+      RetentionAction = "Alla scadenza",
+      RetentionToTrash = "Sposta nel Cestino",
+      RetentionPurge = "Elimina in modo permanente",
       RetentionRun = "Esegui ora",
       LocalStore = "Archivio locale",
       LocalStoreAppData = "Dati app (predefinito)",

src/MaksIT.PostClient.Shared/UiCopy.de.cs

@@ -60,8 +60,11 @@ public sealed partial class UiCopy {
       DetachStoreDone = "{0} gelöst. Der Ordner bleibt auf der Platte.",
       MoveStoreDone = "Speicher {0} verschoben.",
       Retention = "_Aufbewahrung…",
-      RetentionHint = "Pro Ordner. 0 behält dauerhaft. Eine Tageszahl löscht ältere Nachrichten endgültig (nicht in den Papierkorb).",
+      RetentionHint = "Pro Ordner. 0 behält dauerhaft. Ordner-Tage verschieben ältere Nachrichten in den Papierkorb. Papierkorb-Tage löschen endgültig, oder 0 behält den Papierkorb dauerhaft.",
       RetentionDays = "Tage",
+      RetentionAction = "Nach Ablauf",
+      RetentionToTrash = "In den Papierkorb",
+      RetentionPurge = "Endgültig löschen",
       RetentionRun = "Jetzt ausführen",
       LocalStore = "Lokaler Speicher",
       LocalStoreAppData = "App-Daten (Standard)",

src/MaksIT.PostClient.Shared/UiCopy.es.cs

@@ -60,8 +60,11 @@ public sealed partial class UiCopy {
       DetachStoreDone = "Desadjuntado {0}. La carpeta sigue en el disco.",
       MoveStoreDone = "Almacén {0} movido.",
       Retention = "_Retención…",
-      RetentionHint = "Por carpeta. 0 conserva para siempre. Un número de días borra de forma permanente los mensajes más antiguos (no a la Papelera).",
+      RetentionHint = "Por carpeta. 0 conserva para siempre. Los días de la carpeta envían los mensajes antiguos a la Papelera. Los días de la Papelera borran de forma permanente, o 0 para conservarla siempre.",
       RetentionDays = "Días",
+      RetentionAction = "Al caducar",
+      RetentionToTrash = "Mover a la Papelera",
+      RetentionPurge = "Eliminar de forma permanente",
       RetentionRun = "Ejecutar ahora",
       LocalStore = "Almacén local",
       LocalStoreAppData = "Datos de la app (predeterminado)",

src/MaksIT.PostClient.Shared/UiCopy.fr.cs

@@ -60,8 +60,11 @@ public sealed partial class UiCopy {
       DetachStoreDone = "{0} détaché. Le dossier reste sur le disque.",
       MoveStoreDone = "Magasin {0} déplacé.",
       Retention = "_Rétention…",
-      RetentionHint = "Par dossier. 0 conserve pour toujours. Un nombre de jours supprime définitivement les messages plus anciens (pas la Corbeille).",
+      RetentionHint = "Par dossier. 0 conserve pour toujours. Les jours du dossier envoient les messages plus anciens vers la Corbeille. Les jours de la Corbeille suppriment définitivement, ou 0 pour la garder pour toujours.",
       RetentionDays = "Jours",
+      RetentionAction = "À l’échéance",
+      RetentionToTrash = "Déplacer vers la Corbeille",
+      RetentionPurge = "Supprimer définitivement",
       RetentionRun = "Exécuter maintenant",
       LocalStore = "Magasin local",
       LocalStoreAppData = "Données de l’app (défaut)",

src/MaksIT.PostClient.Tests/OutlookRulesTests.cs

@@ -174,6 +174,29 @@ public class MailRuleEngineTests {
 }
 
 
+public class MailRetentionTests {
+  [Fact]
+  public void Jobs_SkipsZeroDays() {
+    var jobs = MailRetention.Jobs(
+      [
+        new FolderRetention { MailboxId = "box", Folder = "INBOX", Days = 0 },
+        new FolderRetention { MailboxId = "box", Folder = "Pratiche", Days = 30 }
+      ]);
+    var job = Assert.Single(jobs);
+    Assert.Equal("box", job.MailboxId);
+    Assert.Equal("Pratiche", job.Folder);
+    Assert.Equal(30, job.Days);
+  }
+
+  [Fact]
+  public void ResolveTrash_PrefersExistingTrashFolder() {
+    Assert.Equal("Cestino", MailRetention.ResolveTrash(["INBOX", "Cestino"]));
+    Assert.Equal(MailRetention.TrashFolder, MailRetention.ResolveTrash(["INBOX"]));
+    Assert.True(MailRetention.IsTrash("Deleted Items"));
+  }
+}
+
+
 public class MapiRestrictionTests {
   [Fact]
   public void Parse_SubjectContainsAndMarkRead() {

src/MaksIT.PostClient.Tests/ProtocolTests.cs

@@ -430,6 +430,53 @@ public class PstMailSessionTests {
 }
 
 
+public class LocalStoreSessionTests {
+  [Fact]
+  public async Task EmptyFolder_MovesToTrash() {
+    var dir = Path.Combine(Path.GetTempPath(), "postclient-store-" + Guid.NewGuid().ToString("N"));
+    Directory.CreateDirectory(dir);
+    try {
+      var box = new MailboxAccount {
+        IncomingProtocol = MailProtocol.Store,
+        Provider = MailProvider.Store,
+        StorePath = dir
+      };
+      LocalStoreSidecar.Write(dir, box.Id, "Mail");
+      MailArchiveLayout.EnsureSystemFolders(dir);
+      await using var session = new LocalStoreSession();
+      var token = TestContext.Current.CancellationToken;
+      var connected = await session.ConnectAsync(box, "", token);
+      Assert.True(connected.IsSuccess, string.Join(" ", connected.Messages));
+      var appended = await session.AppendAsync("Inbox", StoreEml("keep"), token);
+      Assert.True(appended.IsSuccess, string.Join(" ", appended.Messages));
+      var listed = await session.ListMessagesAsync("Inbox", null, token);
+      Assert.True(listed.IsSuccess, string.Join(" ", listed.Messages));
+      Assert.Single(listed.Value!.Present!);
+      var emptied = await session.EmptyFolderAsync("Inbox", MailRetention.TrashFolder, token);
+      Assert.True(emptied.IsSuccess, string.Join(" ", emptied.Messages));
+      var inbox = await session.ListMessagesAsync("Inbox", null, token);
+      Assert.True(inbox.IsSuccess, string.Join(" ", inbox.Messages));
+      Assert.Empty(inbox.Value!.Present ?? []);
+      var trash = await session.ListMessagesAsync(MailRetention.TrashFolder, null, token);
+      Assert.True(trash.IsSuccess, string.Join(" ", trash.Messages));
+      Assert.Single(trash.Value!.Present ?? []);
+    }
+    finally {
+      if (Directory.Exists(dir))
+        Directory.Delete(dir, recursive: true);
+    }
+  }
+
+  private static byte[] StoreEml(string subject) =>
+    System.Text.Encoding.ASCII.GetBytes(
+      "From: test@example.com\r\nTo: you@example.com\r\nSubject: "
+      + subject
+      + "\r\nDate: Mon, 14 Sep 2026 08:00:00 +0000\r\nMessage-ID: <"
+      + subject
+      + "@example.com>\r\nMIME-Version: 1.0\r\nContent-Type: text/plain; charset=utf-8\r\n\r\nbody\r\n");
+}
+
+
 public class MailSessionGateTests {
   [Fact]
   public async Task RunAsync_DoesNotUseCallerSynchronizationContext() {

src/MaksIT.PostClient.Tests/StoreAndHubTests.cs

@@ -439,7 +439,7 @@ public class LocalStoreTests {
   }
 
   [Fact]
-  public void Retention_ZeroKeeps_PositiveDeletesPermanently() {
+  public void Retention_ZeroKeeps_PositiveMovesToTrashThenPurgesTrash() {
     var root = Path.Combine(Path.GetTempPath(), "postclient-ret-" + Guid.NewGuid().ToString("N"));
     Directory.CreateDirectory(root);
     var settings = Path.Combine(root, "settings.json");
@@ -472,6 +472,15 @@ public class LocalStoreTests {
         "");
       File.WriteAllText(Path.Combine(root, "1.eml"), "old");
       var files = new ConfigurationFileService(settings);
+      files.Current.Mailboxes =
+      [
+        new MailboxAccount {
+          Id = "box",
+          IncomingProtocol = MailProtocol.Store,
+          Provider = MailProvider.Store,
+          StorePath = root
+        }
+      ];
       files.Current.Retention =
       [
         new FolderRetention { MailboxId = "box", Folder = "INBOX", Days = 0 }
@@ -490,7 +499,23 @@ public class LocalStoreTests {
       var left = catalog.Search("box", "INBOX", "IMU");
       Assert.Single(left);
       Assert.Equal(2u, left[0].Uid);
+      var trashed = catalog.Search("box", MailRetention.TrashFolder, "IMU");
+      Assert.Single(trashed);
+      Assert.Equal("Old", trashed[0].Subject);
       Assert.False(File.Exists(Path.Combine(root, "1.eml")));
+      Assert.True(File.Exists(MailArchiveLayout.EmlPath(
+        files.Current.Mailboxes[0],
+        files.Current.Mailboxes,
+        MailRetention.TrashFolder,
+        trashed[0].Uid)));
+      files.Current.Retention =
+      [
+        new FolderRetention { MailboxId = "box", Folder = MailRetention.TrashFolder, Days = 5 }
+      ];
+      files.Save(files.Current);
+      using var purgeHost = new MailWorkerHost(catalog, files);
+      purgeHost.Retention(new WorkerRequest { Op = "retention" });
+      Assert.Empty(catalog.Search("box", MailRetention.TrashFolder, "IMU"));
     }
     finally {
       Directory.Delete(root, recursive: true);

src/MaksIT.PostClient.UI/ViewModels/MainViewModel.cs

@@ -987,26 +987,47 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
   public async Task RunRetentionAsync() {
     var configuration = _files.Current;
     configuration.EnsureDefaults();
-    foreach (var rule in configuration.Retention) {
+    foreach (var job in MailRetention.Jobs(configuration.Retention)) {
-      if (rule.Days <= 0 || string.IsNullOrWhiteSpace(rule.MailboxId) || string.IsNullOrWhiteSpace(rule.Folder))
+      var box = Mailboxes.FirstOrDefault(m => m.Id.Equals(job.MailboxId, StringComparison.OrdinalIgnoreCase));
-        continue;
-      var box = Mailboxes.FirstOrDefault(m => m.Id.Equals(rule.MailboxId, StringComparison.OrdinalIgnoreCase));
       if (box is null || box.IsLocalStore)
         continue;
-      var cutoff = DateTimeOffset.UtcNow.AddDays(-rule.Days);
+      var known = FoldersFor(box).Select(f => f.FullName).ToList();
-      var ids = _archive.UidsOlderThan(rule.MailboxId, rule.Folder, cutoff);
+      if (known.Count == 0)
+        known = _archive.ListFolders(box.Id).ToList();
+      var folder = MailRetention.BindFolder(job.Folder, known);
+      if (string.IsNullOrWhiteSpace(folder))
+        continue;
+      var cutoff = DateTimeOffset.UtcNow.AddDays(-job.Days);
+      var ids = _archive.UidsOlderThan(box.Id, folder, cutoff);
       if (ids.Count == 0)
         continue;
       var session = SessionFor(box);
-      if (session is { IsConnected: true })
+      if (session is not { IsConnected: true })
-        await session.SetMessageFlagsAsync(rule.Folder, ids, new MailFlagUpdate { Deleted = true });
+        continue;
+      if (MailRetention.IsTrash(folder)) {
+        await session.SetMessageFlagsAsync(folder, ids, new MailFlagUpdate { Deleted = true });
+        continue;
+      }
+
+      if (session is not { SupportsFolders: true })
+        continue;
+      var trash = MailRetention.ResolveTrash(
+        FoldersFor(box).Select(f => (f.Name, f.FullName)).ToList());
+      if (folder.Equals(trash, StringComparison.OrdinalIgnoreCase)) {
+        await session.SetMessageFlagsAsync(folder, ids, new MailFlagUpdate { Deleted = true });
+        continue;
+      }
+
+      var moved = await session.MoveMessagesAsync(folder, ids, trash, CancellationToken.None);
+      if (moved.IsSuccess)
+        DropArchived(box.Id, folder, ids);
     }
 
     var result = await Task.Run(() => _worker.Call(new WorkerRequest { Op = "retention" }))
       .ConfigureAwait(false);
     await Dispatcher.UIThread.InvokeAsync(() => {
       Status = result.Ok
-        ? "Retention deleted " + (result.Value ?? "0") + " messages."
+        ? "Retention processed " + (result.Value ?? "0") + " messages."
         : result.Error ?? "Retention failed.";
     });
     if (SelectedFolder is not null)
@@ -1598,20 +1619,22 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     var rows = TargetRows();
     if (rows.Count == 0)
       return;
-    var trash = Folders.Concat(FoldersFor(SelectedMailbox))
+    var box = SelectedMailbox;
-      .FirstOrDefault(f => MailFolderRole.Kind(f.Name, f.FullName) == "trash");
+    var folder = SelectedFolder;
-    if (trash is not null
+    if (box is null || folder is null)
-        && SelectedFolder is not null
-        && !trash.FullName.Equals(SelectedFolder.FullName, StringComparison.OrdinalIgnoreCase)) {
-      await MoveRowsAsync(rows, trash.FullName);
       return;
+    if (!MailRetention.IsTrash(folder.Name, folder.FullName)) {
+      var trash = await EnsureTrashFolderAsync(box, CancellationToken.None);
+      if (!string.IsNullOrWhiteSpace(trash)
+          && !trash.Equals(folder.FullName, StringComparison.OrdinalIgnoreCase)) {
+        await MoveRowsAsync(rows, trash);
+        return;
+      }
     }
 
     if (!await ApplyFlagsAsync(new MailFlagUpdate { Deleted = true }, null, rows))
       return;
-    if (SelectedMailbox is null || SelectedFolder is null)
+    DropArchived(box.Id, folder.FullName, TargetIds(rows));
-      return;
-    DropArchived(SelectedMailbox.Id, SelectedFolder.FullName, TargetIds(rows));
     RemoveRows(rows);
     Status = "Deleted.";
   }
@@ -1647,17 +1670,16 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     var folder = SelectedFolder;
     if (session is not { IsConnected: true, SupportsFolders: true } || box is null || folder is null)
       return;
-    var trash = Folders.Concat(FoldersFor(SelectedMailbox))
+    var trash = await EnsureTrashFolderAsync(box, CancellationToken.None);
-      .FirstOrDefault(f => MailFolderRole.Kind(f.Name, f.FullName) == "trash");
+    var purge = string.IsNullOrWhiteSpace(trash)
-    var purge = trash is null
+      || trash.Equals(folder.FullName, StringComparison.OrdinalIgnoreCase);
-      || trash.FullName.Equals(folder.FullName, StringComparison.OrdinalIgnoreCase);
     var confirm = string.Format(purge ? Copy.EmptyTrashConfirm : Copy.EmptyFolderConfirm, folder.Name);
     if (!await ConfirmAsync(Copy.EmptyFolder, confirm))
       return;
     await RunAsync(Copy.EmptyingFolder, async token => {
       var result = await session.EmptyFolderAsync(
         folder.FullName,
-        purge ? null : trash!.FullName,
+        purge ? null : trash,
         token);
       if (!result.IsSuccess) {
         Status = string.Join(" ", result.Messages);
@@ -2687,6 +2709,30 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     return _foldersByMailbox.TryGetValue(box.Id, out var rows) ? rows : [];
   }
 
+  private FolderRowViewModel? TrashFolderOf(MailboxAccount? box) {
+    if (box is null)
+      return null;
+    return FoldersFor(box)
+      .Concat(Folders)
+      .FirstOrDefault(f => MailRetention.IsTrash(f.Name, f.FullName));
+  }
+
+  private async Task<string?> EnsureTrashFolderAsync(MailboxAccount box, CancellationToken token) {
+    var existing = TrashFolderOf(box);
+    if (existing is not null)
+      return existing.FullName;
+    var session = SessionFor(box);
+    if (session is not { IsConnected: true, SupportsFolders: true })
+      return null;
+    var created = await session.CreateFolderAsync(MailRetention.TrashFolder, null, token);
+    if (!created.IsSuccess)
+      created = await session.CreateFolderAsync("Trash", null, token);
+    if (created.IsSuccess)
+      await LoadFoldersAsync(box, session, token);
+    return TrashFolderOf(box)?.FullName
+      ?? (created.IsSuccess ? MailRetention.TrashFolder : null);
+  }
+
   private IReadOnlyList<MailRule> ActiveRules() =>
     _files.Current.Rules ?? [];
 
@@ -2794,7 +2840,7 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
           continue;
         touched.Add(header.Id);
         if (rule.Action == MailRuleAction.Delete) {
-          var trash = MailRuleEngine.ResolveFolder("Trash", folders);
+          var trash = MailRetention.ResolveTrash(folders);
           if (!string.IsNullOrWhiteSpace(trash))
             AddUid(moves, trash, header.Id);
         }
@@ -2908,7 +2954,7 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
       return;
     var unique = copied.Distinct().ToList();
     if (sourceSession is { IsConnected: true, SupportsFolders: true }) {
-      var trash = MailRuleEngine.ResolveFolder("Trash", sourceFolders);
+      var trash = MailRetention.ResolveTrash(sourceFolders);
       if (!string.IsNullOrWhiteSpace(trash) && !trash.Equals(sourceFolder, StringComparison.OrdinalIgnoreCase))
         await sourceSession.MoveMessagesAsync(sourceFolder, unique, trash, token);
       else
@@ -4107,11 +4153,11 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     if (ids.Count == 0)
       return;
     if (session is { IsConnected: true, SupportsFolders: true }) {
-      var trash = FoldersFor(source)
+      var trash = MailRetention.ResolveTrash(
-        .FirstOrDefault(f => MailFolderRole.Kind(f.Name, f.FullName) == "trash");
+        FoldersFor(source).Select(f => (f.Name, f.FullName)).ToList());
-      if (trash is not null
+      if (!string.IsNullOrWhiteSpace(trash)
-          && !trash.FullName.Equals(sourceFolder, StringComparison.OrdinalIgnoreCase))
+          && !trash.Equals(sourceFolder, StringComparison.OrdinalIgnoreCase))
-        await session.MoveMessagesAsync(sourceFolder, ids, trash.FullName, token);
+        await session.MoveMessagesAsync(sourceFolder, ids, trash, token);
       else
         await session.SetMessageFlagsAsync(sourceFolder, ids, new MailFlagUpdate { Deleted = true }, token);
     }

src/MaksIT.PostClient.UI/ViewModels/RetentionViewModel.cs

@@ -14,6 +14,11 @@ public sealed class RetentionRowViewModel : ObservableObject {
 
   public required string Folder { get; init; }
 
+  public required bool IsTrash { get; init; }
+
+  public string ActionLabel =>
+    IsTrash ? UiLocale.Copy.RetentionPurge : UiLocale.Copy.RetentionToTrash;
+
   private int _days;
 
   public int Days {
@@ -38,8 +43,10 @@ public sealed partial class RetentionViewModel : ObservableObject {
     foreach (var box in mailboxes) {
       var listed = folders(box.Id);
       var names = listed.Count > 0
-        ? listed.Select(f => f.FullName)
+        ? listed.Select(f => f.FullName).ToList()
-        : MailArchiveLayout.SystemFolders;
+        : MailArchiveLayout.SystemFolders.ToList();
+      if (!names.Any(folder => MailRetention.IsTrash(folder)))
+        names.Add(MailRetention.TrashFolder);
       foreach (var folder in names.Distinct(StringComparer.OrdinalIgnoreCase)) {
         var rule = saved.FirstOrDefault(r =>
           r.MailboxId.Equals(box.Id, StringComparison.OrdinalIgnoreCase)
@@ -48,6 +55,7 @@ public sealed partial class RetentionViewModel : ObservableObject {
           MailboxId = box.Id,
           MailboxLabel = box.Label,
           Folder = folder,
+          IsTrash = MailRetention.IsTrash(folder),
           Days = rule?.Days ?? 0
         });
       }

src/MaksIT.PostClient.UI/Windows/RetentionWindow.axaml

@@ -41,6 +41,10 @@
                             Binding="{Binding Folder}"
                             IsReadOnly="True"
                             Width="*" />
+        <DataGridTextColumn Header="{Binding Copy.RetentionAction, ElementName=Root}"
+                            Binding="{Binding ActionLabel}"
+                            IsReadOnly="True"
+                            Width="140" />
         <DataGridTextColumn Header="{Binding Copy.RetentionDays, ElementName=Root}"
                             Binding="{Binding Days}"
                             Width="90" />