diff --git a/configuration.nix b/configuration.nix
index 8d25997..7742705 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -110,8 +110,6 @@
     };
   };
 
-  services.flatpak.enable = true;
-
   services.displayManager.gdm.enable = true;
   services.desktopManager.gnome.enable = true;
   services.gnome.sushi.enable = true;
@@ -253,7 +251,6 @@
 
   environment.systemPackages = with pkgs; [
     bubblewrap
-    flatpak
     wget
     nh
   ];
diff --git a/flake.lock b/flake.lock
index 2b9ad7f..b75d776 100644
--- a/flake.lock
+++ b/flake.lock
@@ -180,11 +180,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1775356232,
-        "narHash": "sha256-oHbYzFPE2PoqfGKEQrLeSuJi944SvOCzNvcqQ5WHFjw=",
+        "lastModified": 1775325653,
+        "narHash": "sha256-dlopJjB8mZ3wE4HEUgQOE79zy/rutmG5m96ehAwmTWU=",
         "owner": "nix-community",
         "repo": "NUR",
-        "rev": "4755536f14c499dbfeabc316ba0650193d116bc1",
+        "rev": "63115094168cdfc8a4c09261f3f2fc9838f3affa",
         "type": "github"
       },
       "original": {
@@ -228,11 +228,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1775349555,
-        "narHash": "sha256-4QuGX/NCAqojvTxatzZ0NiWuAV4EAOXU3UdlWsrYVAE=",
+        "lastModified": 1775278263,
+        "narHash": "sha256-BgkUmlOuFaaZQCnlhXkQ3/Fng65aq00tJQkpoeTn7Mw=",
         "owner": "0xc000022070",
         "repo": "zen-browser-flake",
-        "rev": "92cc7e68329b4e394fd1282d412029d550444628",
+        "rev": "bb051d7a0f04356d42528bbb65dc014adf2dab66",
         "type": "github"
       },
       "original": {
diff --git a/home.nix b/home.nix
index 5e260f4..0822516 100644
--- a/home.nix
+++ b/home.nix
@@ -43,11 +43,11 @@ let
     terminal = false;
     categories = [ "Network" ];
   };
-  betterbirdStartup = pkgs.makeDesktopItem {
-    name = "betterbird-startup";
-    desktopName = "Betterbird Startup";
-    comment = "Launch Betterbird in fullscreen";
-    exec = "${pkgs.flatpak}/bin/flatpak run eu.betterbird.Betterbird --fullscreen";
+  thunderbirdStartup = pkgs.makeDesktopItem {
+    name = "thunderbird-startup";
+    desktopName = "Thunderbird Startup";
+    comment = "Launch Thunderbird in fullscreen";
+    exec = "${pkgs.thunderbird}/bin/thunderbird --fullscreen";
     terminal = false;
     categories = [ "Network" ];
   };
@@ -716,24 +716,6 @@ in
     noDisplay = true;
   };
 
-  xdg.desktopEntries.betterbird = {
-    name = "Betterbird";
-    genericName = "Mail Client";
-    exec = "${pkgs.flatpak}/bin/flatpak run eu.betterbird.Betterbird %u";
-    icon = "eu.betterbird.Betterbird";
-    type = "Application";
-    categories = [
-      "Network"
-      "Email"
-    ];
-    mimeType = [
-      "x-scheme-handler/mailto"
-      "x-scheme-handler/webcal"
-      "text/calendar"
-    ];
-    comment = "Fine-tuned Thunderbird mail client";
-  };
-
   # Autostart applications using proper desktop files
   xdg.autostart = {
     enable = true;
@@ -741,7 +723,7 @@ in
       zenStartup
       kittyZellijStartup
       signalStartup
-      betterbirdStartup
+      thunderbirdStartup
       vesktopStartup
       zulipStartup
     ];
@@ -778,7 +760,6 @@ in
       "x-scheme-handler/https" = "zen-beta.desktop";
       "x-scheme-handler/about" = "zen-beta.desktop";
       "x-scheme-handler/unknown" = "zen-beta.desktop";
-      "x-scheme-handler/mailto" = "betterbird.desktop";
       "inode/directory" = "org.gnome.Nautilus.desktop";
       "application/zip" = "org.gnome.FileRoller.desktop";
       "application/x-tar" = "org.gnome.FileRoller.desktop";
@@ -793,6 +774,97 @@ in
     };
   };
 
+  programs.thunderbird = {
+    enable = true;
+    profiles.default = {
+      isDefault = true;
+      settings = {
+        # Use maildir instead of mbox — faster for large mailboxes
+        "mail.serverDefaultStoreContractID" = "@mozilla.org/msgstore/maildirstore;1";
+
+        # Increase IMAP connection limits
+        "mail.server.default.max_cached_connections" = 10;
+        "mail.imap.max_cached_connections" = 10;
+
+        # IMAP IDLE — server pushes new mail instantly (no polling delay)
+        "mail.server.default.use_idle" = true;
+
+        # Poll every 1 minute as fallback when IDLE drops
+        "mail.server.default.check_new_mail" = true;
+        "mail.server.default.check_time" = 1;
+
+        # Faster IMAP sync
+        "mail.imap.min_time_between_cleanups" = 300;
+        "mail.imap.fetch_by_chunks" = true;
+        "mail.imap.chunk_size" = 65536;
+        "mail.imap.chunk_add" = 16384;
+
+        # Reduce timeouts (fail fast instead of hanging)
+        "mail.server.default.timeout" = 60;
+        "mailnews.tcptimeout" = 60;
+
+        # Network performance
+        "network.http.max-connections" = 48;
+        "network.http.max-persistent-connections-per-server" = 10;
+        "network.dns.disablePrefetch" = false;
+
+        # Cache messages offline for instant reading
+        "mail.server.default.offline_download" = true;
+        "mail.server.default.download_on_biff" = true;
+
+        # Auto-compact folders when >20MB wasted (keeps mbox files lean)
+        "mail.purge_threshhold_mb" = 20;
+        "mail.prompt_purge_threshhold" = false;
+
+        # Block remote content by default (tracking pixels, slow image loads)
+        "mailnews.message_display.disable_remote_image" = true;
+
+        # Disable adaptive junk filter (server-side spam is better)
+        "mail.spam.manualMark" = true;
+        "mailnews.ui.junk.firstuse" = false;
+        "mailnews.ui.junk.manualMarkAsJunkMarksRead" = true;
+
+        # Prefetch next message while reading current one
+        "mail.server.default.autosync_offline_stores" = true;
+
+        # Open links in default browser (Zen) instead of Thunderbird's internal browser
+        "network.protocol-handler.warn-external.http" = false;
+        "network.protocol-handler.warn-external.https" = false;
+        "network.protocol-handler.expose-all" = true;
+
+        # Simplify message rendering
+        "mailnews.display.prefer_plaintext" = false;
+        "mailnews.display.disallow_mime_handlers" = 0;
+        "mailnews.display.html_as" = 0;
+
+        # Disable return receipt prompts
+        "mail.incorporate.return_receipt" = 0;
+        "mail.receipt.request_return_receipt_on" = false;
+
+        # Disable chat and calendar background connections
+        "mail.chat.enabled" = false;
+        "calendar.integration.notify" = false;
+
+        # Disable unnecessary features
+        "mail.phishing.detection.enabled" = false;
+        "mail.rights.version" = 1;
+        "mail.shell.checkDefaultClient" = false;
+        "mail.spotlight.enable" = false;
+
+        # Faster UI rendering
+        "gfx.webrender.all" = true;
+
+        # Network keepalive
+        "network.http.keep-alive.timeout" = 600;
+        "network.http.response.timeout" = 120;
+
+        # Fix UI not updating after delete/archive — move to next message automatically
+        "mail.delete_matches_sort_order" = true;
+        "mail.advance_on_delete" = true;
+      };
+    };
+  };
+
   home.file.".claude/settings.json".text = builtins.toJSON {
     allowedTools = [
       "Read"