diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..3cf33e9
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,53 @@
+# Unix-style newlines with a newline ending every file
+# copied from in2code/powermail
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+indent_size = 4
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+# TS/JS-Files
+[*.{ts,js}]
+indent_size = 2
+
+# composer.json
+# composer.json currently deviates from default by using 2 spaces indents
+[composer.json]
+indent_size = 2
+
+# JSON-Files
+[*.json]
+indent_style = tab
+
+# ReST-Files (TYPO3 core convention is no longer 3 spaces, it is 4 spaces)
+[*.{rst,rst.txt}]
+indent_size = 4
+max_line_length = 80
+
+# YAML-Files
+[*.{yaml,yml}]
+indent_size = 2
+
+# package.json
+# .travis.yml
+[{package.json,.travis.yml}]
+indent_size = 2
+
+# TypoScript
+[*.{typoscript,tsconfig}]
+indent_size = 2
+
+# XLF-Files
+[*.xlf]
+indent_style = tab
+
+# SQL-Files
+[*.sql]
+indent_style = tab
+indent_size = 2
+
+# .htaccess
+[{_.htaccess,.htaccess}]
+indent_style = tab
diff --git a/.gitattributes b/.gitattributes
index c9a6185..112f5cf 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1 +1,5 @@
 *.gz filter=lfs diff=lfs merge=lfs -text
+/.editorconfig export-ignore
+/.github export-ignore
+/.project export-ignore
+/Tests  export-ignore
diff --git a/.github/workflows/testing.yaml b/.github/workflows/testing.yaml
new file mode 100644
index 0000000..76f3d0f
--- /dev/null
+++ b/.github/workflows/testing.yaml
@@ -0,0 +1,102 @@
+# currently only testing with v12 and supported PHP versions for v12 (8.1-8.4)
+# todo
+# - execute "composer fix:php:cs" and uncomment "php-cs-fixer" job
+# - fix TypoScript linter and uncomment jog
+name: testing
+on:
+  push:
+    branches-ignore:
+      - 'l10n_*'
+  pull_request:
+    branches-ignore:
+      - 'l10n_*'
+
+jobs:
+  php-lint:
+    name: "PHP linter"
+    runs-on: ubuntu-24.04
+    steps:
+      - name: "Checkout"
+        uses: actions/checkout@v4
+      - name: "Install PHP"
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: "${{ matrix.php-version }}"
+          coverage: none
+          tools: composer:v2
+      - name: "Run PHP lint"
+        run: "composer test:php:lint"
+    strategy:
+      fail-fast: false
+      matrix:
+        php-version:
+          - 8.1
+          - 8.2
+          - 8.3
+          - 8.4
+  #typoscript-lint:
+  #  name: "TypoScript linter"
+  #  runs-on: ubuntu-24.04
+  #  steps:
+  #    - name: "Checkout"
+  #      uses: actions/checkout@v4
+  #    - name: "Run TypoScript lint"
+  #      uses: TYPO3-Continuous-Integration/TYPO3-CI-Typoscript-Lint@v1
+  #      with:
+  #        files: "./Configuration"
+  #        config_file: ".project/tests/typoscript-lint.yml"
+  #php-cs-fixer:
+  #  name: "PHP CS Fixer"
+  #  runs-on: ubuntu-24.04
+  #  needs: php-lint
+  #  steps:
+  #    - name: "Checkout"
+  #      uses: actions/checkout@v4
+  #    - name: "Install PHP"
+  #      uses: shivammathur/setup-php@v2
+  #      with:
+  #        php-version: 8.1
+  #    - name: "Composer Install"
+  #      run: "composer install"
+  #    - name: "Run PHP CS Fixer"
+  #      run: "composer test:php:cs"
+  phpstan:
+    name: "PHPstan"
+    runs-on: ubuntu-24.04
+    needs: php-lint
+    steps:
+      - name: "Checkout"
+        uses: actions/checkout@v4
+      - name: "Install PHP"
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 8.1
+      - name: "Composer Install"
+        run: "composer install"
+      - name: "Run PHPstan"
+        run: "composer test:php:phpstan"
+  #unit-tests:
+  #  name: "PHP Unit Tests"
+  #  runs-on: ubuntu-24.04
+  #  needs: php-lint
+  #  steps:
+  #    - name: Checkout
+  #      uses: actions/checkout@v4
+  #    - name: "Install PHP"
+  #      uses: shivammathur/setup-php@v2
+  #      with:
+  #        php-version: "${{ matrix.php-version }}"
+  #        coverage: none
+  #        tools: composer:v2
+  #    - name: "Composer Install"
+  #      run: "composer install"
+  #    - name: "Run Unit Tests"
+  #      run: "composer test:unit"
+    strategy:
+      fail-fast: false
+      matrix:
+        php-version:
+          - 8.1
+          - 8.2
+          - 8.3
+          - 8.4
diff --git a/.project/tests/.php-cs-fixer.php b/.project/tests/.php-cs-fixer.php
new file mode 100644
index 0000000..e2c1e18
--- /dev/null
+++ b/.project/tests/.php-cs-fixer.php
@@ -0,0 +1,111 @@
+<?php
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+/**
+ * This file represents the configuration for Code Sniffing PSR-2-related
+ * automatic checks of coding guidelines
+ * Install @fabpot's great php-cs-fixer tool via
+ *
+ *  $ composer global require friendsofphp/php-cs-fixer
+ *
+ * And then simply run
+ *
+ *  $ php-cs-fixer fix --config ../Build/.php_cs
+ *
+ * inside the TYPO3 directory. Warning: This may take up to 10 minutes.
+ *
+ * For more information read:
+ *     https://www.php-fig.org/psr/psr-2/
+ *     https://cs.sensiolabs.org
+ */
+if (PHP_SAPI !== 'cli') {
+    die('This script supports command line usage only. Please check your command.');
+}
+// Define in which folders to search and which folders to exclude
+// Exclude some directories that are excluded by Git anyways to speed up the sniffing
+$finder = PhpCsFixer\Finder::create()
+    ->in(
+        [
+            __DIR__ . '/../../Classes',
+            __DIR__ . '/../../Tests',
+            __DIR__ . '/../../Configuration',
+        ]
+    );
+// Return a Code Sniffing configuration using
+// all sniffers needed for PSR-2
+// and additionally:
+//  - Remove leading slashes in use clauses.
+//  - PHP single-line arrays should not have trailing comma.
+//  - Single-line whitespace before closing semicolon are prohibited.
+//  - Remove unused use statements in the PHP source code
+//  - Ensure Concatenation to have at least one whitespace around
+//  - Remove trailing whitespace at the end of blank lines.
+
+$config = new PhpCsFixer\Config();
+
+return $config
+    ->setRiskyAllowed(true)
+    ->setRules([
+        '@DoctrineAnnotation' => true,
+        '@PSR2' => true,
+        'array_syntax' => ['syntax' => 'short'],
+        'blank_line_after_opening_tag' => true,
+        'braces' => ['allow_single_line_closure' => true],
+        'cast_spaces' => ['space' => 'none'],
+        'compact_nullable_typehint' => true,
+        'concat_space' => ['spacing' => 'one'],
+        'declare_equal_normalize' => ['space' => 'none'],
+        'dir_constant' => true,
+        'function_to_constant' => ['functions' => ['get_called_class', 'get_class', 'get_class_this', 'php_sapi_name', 'phpversion', 'pi']],
+        'function_typehint_space' => true,
+        'lowercase_cast' => true,
+        'method_argument_space' => ['on_multiline' => 'ensure_fully_multiline'],
+        'modernize_strpos' => false, // different to https://github.com/TYPO3/typo3/blob/main/Build/php-cs-fixer.php
+        'modernize_types_casting' => true,
+        'native_function_casing' => true,
+        'new_with_braces' => true,
+        'no_alias_functions' => true,
+        'no_blank_lines_after_phpdoc' => true,
+        'no_empty_phpdoc' => true,
+        'no_empty_statement' => true,
+        'no_extra_blank_lines' => true,
+        'no_leading_import_slash' => true,
+        'no_leading_namespace_whitespace' => true,
+        'no_null_property_initialization' => false, // different to https://github.com/TYPO3/typo3/blob/main/Build/php-cs-fixer.php
+        'no_short_bool_cast' => true,
+        'no_singleline_whitespace_before_semicolons' => true,
+        'no_superfluous_elseif' => true,
+        'no_trailing_comma_in_singleline_array' => true,
+        'no_unneeded_control_parentheses' => true,
+        'no_unused_imports' => true,
+        'no_useless_else' => true,
+        'no_whitespace_in_blank_line' => true,
+        'ordered_imports' => true,
+        'php_unit_construct' => ['assertions' => ['assertEquals', 'assertSame', 'assertNotEquals', 'assertNotSame']],
+        'php_unit_mock_short_will_return' => true,
+        'php_unit_test_case_static_method_calls' => ['call_type' => 'self'],
+        'phpdoc_no_access' => true,
+        'phpdoc_no_empty_return' => false, // different to https://github.com/TYPO3/typo3/blob/main/Build/php-cs-fixer.php
+        'phpdoc_no_package' => true,
+        'phpdoc_scalar' => true,
+        'phpdoc_trim' => true,
+        'phpdoc_types' => true,
+        'phpdoc_types_order' => ['null_adjustment' => 'always_last', 'sort_algorithm' => 'none'],
+        'return_type_declaration' => ['space_before' => 'none'],
+        'single_quote' => true,
+        'single_line_comment_style' => ['comment_types' => ['hash']],
+        'single_trait_insert_per_statement' => true,
+        'trailing_comma_in_multiline' => ['elements' => ['arrays']],
+        'whitespace_after_comma_in_array' => true,
+        'yoda_style' => ['equal' => false, 'identical' => false, 'less_and_greater' => false],
+    ])->setFinder($finder);
diff --git a/.project/tests/phpstan-baseline.neon b/.project/tests/phpstan-baseline.neon
new file mode 100644
index 0000000..b3eda86
--- /dev/null
+++ b/.project/tests/phpstan-baseline.neon
@@ -0,0 +1,6 @@
+parameters:
+	ignoreErrors:
+		-
+			message: "#^Static method In2code\\\\PowermailCleaner\\\\Service\\\\TimeCalculationService\\:\\:getTodaysStart\\(\\) is unused\\.$#"
+			count: 1
+			path: ../../Classes/Service/TimeCalculationService.php
diff --git a/.project/tests/phpstan.neon b/.project/tests/phpstan.neon
new file mode 100644
index 0000000..1daf4e9
--- /dev/null
+++ b/.project/tests/phpstan.neon
@@ -0,0 +1,14 @@
+# tests for v12
+# todo
+# - some phpstan tests will fail due to classes being XCLASSed and the code using the original class, can be explicitly
+#   defined using @var, see Command/CleanupCommand.php
+includes:
+    - phpstan-baseline.neon
+parameters:
+    level: 5
+    tmpDir: ../../.build/var/cache/phpstan
+    paths:
+        - ../../Classes
+    scanDirectories:
+        - ../../.build/vendor/in2code/powermail
+        - ../../.build/vendor/typo3
diff --git a/Classes/Command/CleanupCommand.php b/Classes/Command/CleanupCommand.php
index 5966ca0..1418409 100644
--- a/Classes/Command/CleanupCommand.php
+++ b/Classes/Command/CleanupCommand.php
@@ -25,6 +25,7 @@ protected function configure(): void
     }
     protected function execute(InputInterface $input, OutputInterface $output): int
     {
+        /** @var \In2code\PowermailCleaner\Domain\Repository\MailRepository $mailRepository */
         $mailRepository = GeneralUtility::makeInstance(MailRepository::class);
         $mailsToDelete = $mailRepository->findAllDeletionTimeStampOlderThan(time());
         $mails = 0;
@@ -36,4 +37,4 @@ protected function execute(InputInterface $input, OutputInterface $output): int
         $this->logger->info('Removed mails: ' . $mails);
         return Command::SUCCESS;
     }
-}
\ No newline at end of file
+}
diff --git a/Classes/Command/ForceCleanupCommand.php b/Classes/Command/ForceCleanupCommand.php
index 84b0d53..0c4243f 100644
--- a/Classes/Command/ForceCleanupCommand.php
+++ b/Classes/Command/ForceCleanupCommand.php
@@ -32,6 +32,7 @@ protected function configure(): void
 
     protected function execute(InputInterface $input, OutputInterface $output): int
     {
+        /** @var \In2code\PowermailCleaner\Domain\Repository\MailRepository $mailRepository */
         $mailRepository = GeneralUtility::makeInstance(MailRepository::class);
         // ToDo: calculate timestamp
         $timestamp = (time() - $input->getArgument('Retention days') * 86400);
diff --git a/Classes/Command/InformReceiversCommand.php b/Classes/Command/InformReceiversCommand.php
index 1d43d2e..d6395a4 100644
--- a/Classes/Command/InformReceiversCommand.php
+++ b/Classes/Command/InformReceiversCommand.php
@@ -41,11 +41,8 @@ public function __construct(
     ) {
         parent::__construct();
         $this->powermailCleanerTyposcript = $this->getTypoScriptConfiguration();
-        /** @var MailRepository $mailRepository */
         $this->mailRepository = GeneralUtility::makeInstance(MailRepository::class);
-        /** @var FlexFormService $flexFormService */
         $this->flexFormService = GeneralUtility::makeInstance(FlexFormService::class);
-        /** @var Mail $mail */
         $this->mail = GeneralUtility::makeInstance(Mail::class);
         $this->timeCalculationService = GeneralUtility::makeInstance(TimeCalculationService::class);
     }
@@ -119,7 +116,7 @@ private function getTypoScriptConfiguration(): array
 
     private function findReceivers(array $flexform): array
     {
-        /** @var  ReceiverAddressService $receiverService */
+        /** @var  ReceiverAddressService $addressService */
         $addressService = GeneralUtility::makeInstance(ReceiverAddressService::class, $this->mail, $flexform);
         return $addressService->getReceiverEmails();
     }
diff --git a/Classes/Controller/ModuleController.php b/Classes/Controller/ModuleController.php
index 0f724e6..1a2b72b 100644
--- a/Classes/Controller/ModuleController.php
+++ b/Classes/Controller/ModuleController.php
@@ -12,15 +12,11 @@
  */
 class ModuleController extends \In2code\Powermail\Controller\ModuleController
 {
-    /**
-     * @param int $age
-     * @param int $pid
-     */
     public function cleanupAction(): ResponseInterface
     {
         $age = null;
         $pid = null;
-        
+
         if ($this->request->hasArgument('age')) {
             $age = $this->request->getArgument('age');
         }
diff --git a/Classes/Domain/Repository/MailRepository.php b/Classes/Domain/Repository/MailRepository.php
index a8aee3a..30c74eb 100644
--- a/Classes/Domain/Repository/MailRepository.php
+++ b/Classes/Domain/Repository/MailRepository.php
@@ -155,7 +155,7 @@ public function findMailsOlderThan(int $timestamp): array
 
     /**
      * @param int $mailIdentifier
-     * @return QueryBuilder
+     * @return array
      * @throws Exception
      */
     public function getAnswersWithFiles(int $mailIdentifier): array
diff --git a/Classes/Service/TimeCalculationService.php b/Classes/Service/TimeCalculationService.php
index 231c9e5..5e66985 100644
--- a/Classes/Service/TimeCalculationService.php
+++ b/Classes/Service/TimeCalculationService.php
@@ -15,8 +15,11 @@ public function calculateNotificationTimeframe(int $informReceiversBeforeDeletio
         return $notificationLimit;
     }
 
+    /**
+     * @todo Remove? Is not used
+     */
     private static function getTodaysStart(): int
     {
         return strtotime('today', time());
     }
-}
\ No newline at end of file
+}
diff --git a/Classes/Utility/FileUtility.php b/Classes/Utility/FileUtility.php
index 0d5e2db..e963d4d 100644
--- a/Classes/Utility/FileUtility.php
+++ b/Classes/Utility/FileUtility.php
@@ -80,6 +80,7 @@ public static function hasSysfileReference(int $sysFileUid): bool
 
     public static function deleteFromFilesystem(string $identifier, ?ResourceStorage $storage): void
     {
+        $resourceBasePath = '';
         if ($storage instanceof ResourceStorage) {
             $resourceBasePath = $storage->getConfiguration()['basePath'];
         }
diff --git a/composer.json b/composer.json
index 4463cea..01dfbc7 100644
--- a/composer.json
+++ b/composer.json
@@ -81,14 +81,10 @@
     "friends-of-behat/mink-extension": "^2.7",
     "behat/mink-selenium2-driver": "^1.7",
     "friends-of-behat/mink-browserkit-driver": "^1.6",
-    "drevops/behat-screenshot": "^1.2"
+    "drevops/behat-screenshot": "^1.2",
+    "phpstan/phpstan": "^1.11.7",
+    "saschaegerer/phpstan-typo3": "^1.10.2"
   },
-  "repositories": [
-    {
-      "type": "git",
-      "url": "git@github.com:in2code-pro/powermail.git"
-    }
-  ],
   "autoload": {
     "psr-4": {
       "In2code\\PowermailCleaner\\": "Classes/"
@@ -122,8 +118,11 @@
     "test:behaviour": "behat --config Tests/Behavior/behat.ddev.yml",
     "test:behaviour:tag": "behat --config Tests/Behavior/behat.ddev.yml --tags",
     "test:behaviour:stop": "behat --config Tests/Behavior/behat.ddev.yml --stop-on-failure",
-    "test:php:cs": ".Build/bin/php-cs-fixer --version && .Build/bin/php-cs-fixer fix --dry-run --config=.project/tests/.php-cs-fixer.php --diff",
+    "test:php:cs": ".build/bin/php-cs-fixer --version && .build/bin/php-cs-fixer fix --dry-run --config=.project/tests/.php-cs-fixer.php --diff",
+    "fix:php:cs": ".build/bin/php-cs-fixer --version && .build/bin/php-cs-fixer fix --config=.project/tests/.php-cs-fixer.php --diff",
     "test:php:lint": "find *.php Classes Configuration Tests -name '*.php' -print0 | xargs -0 -n 1 -P 4 php -l",
+    "test:php:phpstan": "phpstan analyse -c .project/tests/phpstan.neon",
+    "test:php:phpstan:generate-baseline": "phpstan analyse -c .project/tests/phpstan.neon --generate-baseline .project/tests/phpstan-baseline.neon",
     "test:typoscript:lint": "typoscript-lint --config=.project/tests/typoscript-lint.yml",
     "test:unit": "phpunit -c phpunit.xml.dist"
   }