diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index b39486cf6..68e0760df 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -312,6 +312,9 @@ Makefile                                              @thiagokokada
 
 /modules/programs/texlive.nix                         @rycee
 
+/modules/programs/thunderbird.nix                     @d-dervishi
+/tests/modules/programs/thunderbird                   @d-dervishi
+
 /modules/programs/timidity.nix                        @amesgen
 
 /modules/programs/tint2.nix                           @CarlosLoboxyz
diff --git a/modules/lib/maintainers.nix b/modules/lib/maintainers.nix
index cbe779682..896e47f68 100644
--- a/modules/lib/maintainers.nix
+++ b/modules/lib/maintainers.nix
@@ -37,12 +37,28 @@
     github = "CarlosLoboxyz";
     githubId = 86011416;
   };
+  d-dervishi = {
+    email = "david.dervishi@epfl.ch";
+    github = "d-dervishi";
+    githubId = 61125355;
+    name = "David Dervishi";
+    keys = [{
+      longKeyId = "rsa4096/0xB1C012F0E7697195";
+      fingerprint = "4C92 E3B0 21B5 5562 A1E0  CE3D B1C0 12F0 E769 7195";
+    }];
+  };
   dwagenk = {
     email = "dwagenk@mailbox.org";
     github = "dwagenk";
     githubId = 32838899;
     name = "Daniel Wagenknecht";
   };
+  jkarlson = {
+    email = "jekarlson@gmail.com";
+    github = "jkarlson";
+    githubId = 1204734;
+    name = "Emil Karlson";
+  };
   justinlovinger = {
     name = "Justin Lovinger";
     email = "git@justinlovinger.com";
diff --git a/modules/misc/news.nix b/modules/misc/news.nix
index bb1e7e2be..34c2e0e1d 100644
--- a/modules/misc/news.nix
+++ b/modules/misc/news.nix
@@ -815,6 +815,14 @@ in
           A new module is available: 'xfconf'.
         '';
       }
+
+      {
+        time = "2022-11-04T14:56:46+00:00";
+        condition = hostPlatform.isLinux;
+        message = ''
+          A new module is available: 'programs.thunderbird';
+        '';
+      }
     ];
   };
 }
diff --git a/modules/modules.nix b/modules/modules.nix
index d465e8caa..a57925ea9 100644
--- a/modules/modules.nix
+++ b/modules/modules.nix
@@ -176,6 +176,7 @@ let
     ./programs/terminator.nix
     ./programs/termite.nix
     ./programs/texlive.nix
+    ./programs/thunderbird.nix
     ./programs/timidity.nix
     ./programs/tint2.nix
     ./programs/tiny.nix
diff --git a/modules/programs/thunderbird.nix b/modules/programs/thunderbird.nix
new file mode 100644
index 000000000..118a98a62
--- /dev/null
+++ b/modules/programs/thunderbird.nix
@@ -0,0 +1,275 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.programs.thunderbird;
+
+  enabledAccounts = attrValues
+    (filterAttrs (_: a: a.thunderbird.enable) config.accounts.email.accounts);
+
+  enabledAccountsWithId =
+    map (a: a // { id = builtins.hashString "sha256" a.name; }) enabledAccounts;
+
+  thunderbirdConfigPath = ".thunderbird";
+
+  profilesWithId =
+    imap0 (i: v: v // { id = toString i; }) (attrValues cfg.profiles);
+
+  profilesIni = foldl recursiveUpdate {
+    General = {
+      StartWithLastProfile = 1;
+      Version = 2;
+    };
+  } (flip map profilesWithId (profile: {
+    "Profile${profile.id}" = {
+      Name = profile.name;
+      Path = profile.name;
+      IsRelative = 1;
+      Default = if profile.isDefault then 1 else 0;
+    };
+  }));
+
+  toThunderbirdAccount = account: profile:
+    let id = account.id;
+    in {
+      "mail.account.account_${id}.identities" = "id_${id}";
+      "mail.account.account_${id}.server" = "server_${id}";
+      "mail.identity.id_${id}.fullName" = account.realName;
+      "mail.identity.id_${id}.useremail" = account.address;
+      "mail.identity.id_${id}.valid" = true;
+    } // optionalAttrs account.primary {
+      "mail.accountmanager.defaultaccount" = "account_${id}";
+    } // optionalAttrs (account.gpg != null) {
+      "mail.identity.id_${id}.attachPgpKey" = false;
+      "mail.identity.id_${id}.autoEncryptDrafts" = true;
+      "mail.identity.id_${id}.e2etechpref" = 0;
+      "mail.identity.id_${id}.encryptionpolicy" =
+        if account.gpg.encryptByDefault then 2 else 0;
+      "mail.identity.id_${id}.is_gnupg_key_id" = true;
+      "mail.identity.id_${id}.last_entered_external_gnupg_key_id" =
+        account.gpg.key;
+      "mail.identity.id_${id}.openpgp_key_id" = account.gpg.key;
+      "mail.identity.id_${id}.protectSubject" = true;
+      "mail.identity.id_${id}.sign_mail" = account.gpg.signByDefault;
+    } // optionalAttrs (account.imap != null) {
+      "mail.server.server_${id}.directory" =
+        "${thunderbirdConfigPath}/${profile.name}/ImapMail/${account.imap.host}";
+      "mail.server.server_${id}.directory-rel" =
+        "[ProfD]ImapMail/${account.imap.host}";
+      "mail.server.server_${id}.hostname" = account.imap.host;
+      "mail.server.server_${id}.login_at_startup" = true;
+      "mail.server.server_${id}.name" = account.name;
+      "mail.server.server_${id}.port" =
+        if (account.imap.port != null) then account.imap.port else 143;
+      "mail.server.server_${id}.socketType" = if !account.imap.tls.enable then
+        0
+      else if account.imap.tls.useStartTls then
+        2
+      else
+        3;
+      "mail.server.server_${id}.type" = "imap";
+      "mail.server.server_${id}.userName" = account.userName;
+    } // optionalAttrs (account.smtp != null) {
+      "mail.identity.id_${id}.smtpServer" = "smtp_${id}";
+      "mail.smtpserver.smtp_${id}.authMethod" = 3;
+      "mail.smtpserver.smtp_${id}.hostname" = account.smtp.host;
+      "mail.smtpserver.smtp_${id}.port" =
+        if (account.smtp.port != null) then account.smtp.port else 587;
+      "mail.smtpserver.smtp_${id}.try_ssl" = if !account.smtp.tls.enable then
+        0
+      else if account.smtp.tls.useStartTls then
+        2
+      else
+        3;
+      "mail.smtpserver.smtp_${id}.username" = account.userName;
+    } // optionalAttrs (account.smtp != null && account.primary) {
+      "mail.smtp.defaultserver" = "smtp_${id}";
+    } // account.thunderbird.settings id;
+
+  mkUserJs = prefs: ''
+    // Generated by Home Manager.
+
+    ${concatStrings (mapAttrsToList (name: value: ''
+      user_pref("${name}", ${builtins.toJSON value});
+    '') prefs)}
+  '';
+in {
+  meta.maintainers = with hm.maintainers; [ d-dervishi jkarlson ];
+
+  options = {
+    programs.thunderbird = {
+      enable = mkEnableOption "Thunderbird";
+
+      package = mkOption {
+        type = types.package;
+        default = pkgs.thunderbird;
+        defaultText = literalExpression "pkgs.thunderbird";
+        example = literalExpression "pkgs.thunderbird-91";
+        description = "The Thunderbird package to use.";
+      };
+
+      profiles = mkOption {
+        type = with types;
+          attrsOf (submodule ({ config, name, ... }: {
+            options = {
+              name = mkOption {
+                type = types.str;
+                default = name;
+                readOnly = true;
+                description = "This profile's name.";
+              };
+
+              isDefault = mkOption {
+                type = types.bool;
+                default = false;
+                example = true;
+                description = ''
+                  Whether this is a default profile. There must be exactly one
+                  default profile.
+                '';
+              };
+
+              settings = mkOption {
+                type = with types; attrsOf (oneOf [ bool int str ]);
+                default = { };
+                example = literalExpression ''
+                  {
+                    "mail.spellcheck.inline" = false;
+                  }
+                '';
+                description = ''
+                  Preferences to add to this profile's
+                  <filename>user.js</filename>.
+                '';
+              };
+
+              withExternalGnupg = mkOption {
+                type = types.bool;
+                default = false;
+                example = true;
+                description = "Allow using external GPG keys with GPGME.";
+              };
+            };
+          }));
+      };
+
+      settings = mkOption {
+        type = with types; attrsOf (oneOf [ bool int str ]);
+        default = { };
+        example = literalExpression ''
+          {
+            "general.useragent.override" = "";
+            "privacy.donottrackheader.enabled" = true;
+          }
+        '';
+        description = ''
+          Attribute set of Thunderbird preferences to be added to
+          all profiles.
+        '';
+      };
+    };
+
+    accounts.email.accounts = mkOption {
+      type = with types;
+        attrsOf (submodule {
+          options.thunderbird = {
+            enable =
+              mkEnableOption "the Thunderbird mail client for this account";
+
+            profiles = mkOption {
+              type = with types; listOf str;
+              default = [ ];
+              example = literalExpression ''
+                [ "profile1" "profile2" ]
+              '';
+              description = ''
+                List of Thunderbird profiles for which this account should be
+                enabled. If this list is empty (the default), this account will
+                be enabled for all declared profiles.
+              '';
+            };
+
+            settings = mkOption {
+              type = with types; functionTo (attrsOf (oneOf [ bool int str ]));
+              default = _: { };
+              defaultText = literalExpression "_: { }";
+              example = literalExpression ''
+                id: {
+                  "mail.identity.id_''${id}.protectSubject" = false;
+                  "mail.identity.id_''${id}.autoEncryptDrafts" = false;
+                };
+              '';
+              description = ''
+                Extra settings to add to this Thunderbird account configuration.
+                The <varname>id</varname> given as argument is an automatically
+                generated account identifier.
+              '';
+            };
+          };
+        });
+    };
+  };
+
+  config = mkIf cfg.enable {
+    assertions = [
+      (hm.assertions.assertPlatform "programs.thunderbird" pkgs platforms.linux)
+
+      (let defaults = catAttrs "name" (filter (a: a.isDefault) profilesWithId);
+      in {
+        assertion = cfg.profiles == { } || length defaults == 1;
+        message = "Must have exactly one default Thunderbird profile but found "
+          + toString (length defaults) + optionalString (length defaults > 1)
+          (", namely " concatStringsSep "," defaults);
+      })
+
+      (let
+        profiles = catAttrs "name" profilesWithId;
+        selectedProfiles =
+          concatMap (a: a.thunderbird.profiles) enabledAccounts;
+      in {
+        assertion = (intersectLists profiles selectedProfiles)
+          == selectedProfiles;
+        message = "Cannot enable an account for a non-declared profile. "
+          + "The declared profiles are " + (concatStringsSep "," profiles)
+          + ", but the used profiles are "
+          + (concatStringsSep "," selectedProfiles);
+      })
+    ];
+
+    home.packages = [ cfg.package ]
+      ++ optional (any (p: p.withExternalGnupg) (attrValues cfg.profiles))
+      pkgs.gpgme;
+
+    home.file = mkMerge ([{
+      "${thunderbirdConfigPath}/profiles.ini" =
+        mkIf (cfg.profiles != { }) { text = generators.toINI { } profilesIni; };
+    }] ++ flip mapAttrsToList cfg.profiles (name: profile: {
+      "${thunderbirdConfigPath}/${name}/user.js" = let
+        accounts = filter (a:
+          a.thunderbird.profiles == [ ]
+          || any (p: p == name) a.thunderbird.profiles) enabledAccountsWithId;
+
+        smtp = filter (a: a.smtp != null) accounts;
+      in {
+        text = mkUserJs (builtins.foldl' (a: b: a // b) { } ([
+          cfg.settings
+
+          (optionalAttrs (length accounts != 0) {
+            "mail.accountmanager.accounts" =
+              concatStringsSep "," (map (a: "account_${a.id}") accounts);
+          })
+
+          (optionalAttrs (length smtp != 0) {
+            "mail.smtpservers" =
+              concatStringsSep "," (map (a: "smtp_${a.id}") smtp);
+          })
+
+          { "mail.openpgp.allow_external_gnupg" = profile.withExternalGnupg; }
+
+          profile.settings
+        ] ++ (map (a: toThunderbirdAccount a profile) accounts)));
+      };
+    }));
+  };
+}
diff --git a/tests/default.nix b/tests/default.nix
index e78e24369..f4f8d877e 100644
--- a/tests/default.nix
+++ b/tests/default.nix
@@ -160,6 +160,7 @@ import nmt {
     ./modules/programs/rofi-pass
     ./modules/programs/swaylock
     ./modules/programs/terminator
+    ./modules/programs/thunderbird
     ./modules/programs/waybar
     ./modules/programs/xmobar
     ./modules/programs/yt-dlp
diff --git a/tests/modules/programs/thunderbird/default.nix b/tests/modules/programs/thunderbird/default.nix
new file mode 100644
index 000000000..487297784
--- /dev/null
+++ b/tests/modules/programs/thunderbird/default.nix
@@ -0,0 +1 @@
+{ thunderbird = ./thunderbird.nix; }
diff --git a/tests/modules/programs/thunderbird/thunderbird-expected-first.js b/tests/modules/programs/thunderbird/thunderbird-expected-first.js
new file mode 100644
index 000000000..6fc45b0e8
--- /dev/null
+++ b/tests/modules/programs/thunderbird/thunderbird-expected-first.js
@@ -0,0 +1,61 @@
+// Generated by Home Manager.
+
+user_pref("general.useragent.override", "");
+user_pref("mail.account.account_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.identities", "id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
+user_pref("mail.account.account_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.server", "server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
+user_pref("mail.account.account_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.identities", "id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f");
+user_pref("mail.account.account_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.server", "server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f");
+user_pref("mail.accountmanager.accounts", "account_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc,account_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f");
+user_pref("mail.accountmanager.defaultaccount", "account_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.autoEncryptDrafts", false);
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.fullName", "H. M. Test Jr.");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.protectSubject", false);
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.smtpServer", "smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.useremail", "hm@example.org");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.valid", true);
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.attachPgpKey", false);
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.autoEncryptDrafts", true);
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.e2etechpref", 0);
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.encryptionpolicy", 0);
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.fullName", "H. M. Test");
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.is_gnupg_key_id", true);
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.last_entered_external_gnupg_key_id", "ABC");
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.openpgp_key_id", "ABC");
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.protectSubject", true);
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.sign_mail", false);
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.smtpServer", "smtp_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f");
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.useremail", "hm@example.com");
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.valid", true);
+user_pref("mail.openpgp.allow_external_gnupg", true);
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.directory", ".thunderbird/first/ImapMail/imap.example.org");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.directory-rel", "[ProfD]ImapMail/imap.example.org");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.hostname", "imap.example.org");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.login_at_startup", true);
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.name", "hm-account");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.port", 143);
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.socketType", 3);
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.type", "imap");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.userName", "home.manager.jr");
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.directory", ".thunderbird/first/ImapMail/imap.example.com");
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.directory-rel", "[ProfD]ImapMail/imap.example.com");
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.hostname", "imap.example.com");
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.login_at_startup", true);
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.name", "hm@example.com");
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.port", 123);
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.socketType", 3);
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.type", "imap");
+user_pref("mail.server.server_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.userName", "home.manager");
+user_pref("mail.smtp.defaultserver", "smtp_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f");
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.authMethod", 3);
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.hostname", "smtp.example.org");
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.port", 587);
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.try_ssl", 2);
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.username", "home.manager.jr");
+user_pref("mail.smtpserver.smtp_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.authMethod", 3);
+user_pref("mail.smtpserver.smtp_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.hostname", "smtp.example.com");
+user_pref("mail.smtpserver.smtp_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.port", 456);
+user_pref("mail.smtpserver.smtp_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.try_ssl", 3);
+user_pref("mail.smtpserver.smtp_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.username", "home.manager");
+user_pref("mail.smtpservers", "smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc,smtp_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f");
+user_pref("privacy.donottrackheader.enabled", true);
+
diff --git a/tests/modules/programs/thunderbird/thunderbird-expected-profiles.ini b/tests/modules/programs/thunderbird/thunderbird-expected-profiles.ini
new file mode 100644
index 000000000..4191f1607
--- /dev/null
+++ b/tests/modules/programs/thunderbird/thunderbird-expected-profiles.ini
@@ -0,0 +1,15 @@
+[General]
+StartWithLastProfile=1
+Version=2
+
+[Profile0]
+Default=1
+IsRelative=1
+Name=first
+Path=first
+
+[Profile1]
+Default=0
+IsRelative=1
+Name=second
+Path=second
diff --git a/tests/modules/programs/thunderbird/thunderbird-expected-second.js b/tests/modules/programs/thunderbird/thunderbird-expected-second.js
new file mode 100644
index 000000000..f18427a95
--- /dev/null
+++ b/tests/modules/programs/thunderbird/thunderbird-expected-second.js
@@ -0,0 +1,31 @@
+// Generated by Home Manager.
+
+user_pref("general.useragent.override", "");
+user_pref("mail.account.account_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.identities", "id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
+user_pref("mail.account.account_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.server", "server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
+user_pref("mail.accountmanager.accounts", "account_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.autoEncryptDrafts", false);
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.fullName", "H. M. Test Jr.");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.protectSubject", false);
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.smtpServer", "smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.useremail", "hm@example.org");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.valid", true);
+user_pref("mail.openpgp.allow_external_gnupg", false);
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.directory", ".thunderbird/second/ImapMail/imap.example.org");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.directory-rel", "[ProfD]ImapMail/imap.example.org");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.hostname", "imap.example.org");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.login_at_startup", true);
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.name", "hm-account");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.port", 143);
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.socketType", 3);
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.type", "imap");
+user_pref("mail.server.server_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.userName", "home.manager.jr");
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.authMethod", 3);
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.hostname", "smtp.example.org");
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.port", 587);
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.try_ssl", 2);
+user_pref("mail.smtpserver.smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.username", "home.manager.jr");
+user_pref("mail.smtpservers", "smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
+user_pref("privacy.donottrackheader.enabled", true);
+user_pref("second.setting", "some-test-setting");
+
diff --git a/tests/modules/programs/thunderbird/thunderbird.nix b/tests/modules/programs/thunderbird/thunderbird.nix
new file mode 100644
index 000000000..ee16efa06
--- /dev/null
+++ b/tests/modules/programs/thunderbird/thunderbird.nix
@@ -0,0 +1,64 @@
+{
+  imports = [ ../../accounts/email-test-accounts.nix ];
+
+  accounts.email.accounts = {
+    "hm@example.com" = {
+      thunderbird = {
+        enable = true;
+        profiles = [ "first" ];
+      };
+
+      gpg.key = "ABC";
+
+      imap = {
+        port = 123;
+        tls.enable = true;
+      };
+      smtp.port = 456;
+    };
+
+    hm-account = {
+      thunderbird = {
+        enable = true;
+        settings = id: {
+          "mail.identity.id_${id}.protectSubject" = false;
+          "mail.identity.id_${id}.autoEncryptDrafts" = false;
+        };
+      };
+    };
+  };
+
+  programs.thunderbird = {
+    enable = true;
+
+    profiles = {
+      first = {
+        isDefault = true;
+        withExternalGnupg = true;
+      };
+
+      second.settings = { "second.setting" = "some-test-setting"; };
+    };
+
+    settings = {
+      "general.useragent.override" = "";
+      "privacy.donottrackheader.enabled" = true;
+    };
+  };
+
+  test.stubs.thunderbird = { };
+
+  nmt.script = ''
+    assertFileExists home-files/.thunderbird/profiles.ini
+    assertFileContent home-files/.thunderbird/profiles.ini \
+      ${./thunderbird-expected-profiles.ini}
+
+    assertFileExists home-files/.thunderbird/first/user.js
+    assertFileContent home-files/.thunderbird/first/user.js \
+      ${./thunderbird-expected-first.js}
+
+    assertFileExists home-files/.thunderbird/second/user.js
+    assertFileContent home-files/.thunderbird/second/user.js \
+      ${./thunderbird-expected-second.js}
+  '';
+}