Thunderbird?

programs/thunderbird.nix

@@ -0,0 +1,8 @@
+{ ... }: {
+  programs.thunderbird.enable = true;
+  
+  programs.thunderbird.profiles.lauren = {
+    isDefault = true;
+    withExternalGnupg = true;
+  };
+}

systems/ll-latitude-e5591.nix

@@ -1,5 +1,9 @@
 #{ pkgs, pkgs-unstable, ... }: {
 { pkgs, ... }: { 
+  imports = [
+    ../programs/thunderbird.nix
+  ];
+  
   home.file = {
     "latitude/tv" = {
       executable = true;