diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a1b046f..d586a0b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,85 +11,85 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php-version: ['7.2', '7.4', '8.0']
+        php-version: ['8.0']
         prefer-lowest: ['']
         include:
           - php-version: '7.2'
             prefer-lowest: 'prefer-lowest'
 
     steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 1
-
-    - name: Setup PHP
-      uses: shivammathur/setup-php@v2
-      with:
-        php-version: ${{ matrix.php-version }}
-        extensions: mbstring, intl
-        coverage: pcov
-
-    - name: Get composer cache directory
-      id: composer-cache
-      run: echo "::set-output name=dir::$(composer config cache-files-dir)"
-
-    - name: Get date part for cache key
-      id: key-date
-      run: echo "::set-output name=date::$(date +'%Y-%m')"
-
-    - name: Cache composer dependencies
-      uses: actions/cache@v2
-      with:
-        path: ${{ steps.composer-cache.outputs.dir }}
-        key: ${{ runner.os }}-composer-${{ steps.key-date.outputs.date }}-${{ hashFiles('composer.json') }}-${{ matrix.prefer-lowest }}
-
-    - name: Composer install
-      run: |
-        if [[ ${{ matrix.php-version }} == '8.0' ]]; then
-          composer install --ignore-platform-reqs
-        elif ${{ matrix.prefer-lowest == 'prefer-lowest' }}; then
-          composer update --prefer-lowest --prefer-stable
-        else
-          composer install
-        fi
-
-    - name: Run PHPUnit
-      run: |
-        if [[ ${{ matrix.php-version }} == '7.4' ]]; then
-          vendor/bin/phpunit --coverage-clover=coverage.xml
-        else
-          vendor/bin/phpunit
-        fi
-
-    - name: Code Coverage Report
-      if: success() && matrix.php-version == '7.4'
-      uses: codecov/codecov-action@v1
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 1
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-version }}
+          extensions: mbstring, intl
+          coverage: pcov
+
+      - name: Get composer cache directory
+        id: composer-cache
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Get date part for cache key
+        id: key-date
+        run: echo "::set-output name=date::$(date +'%Y-%m')"
+
+      - name: Cache composer dependencies
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-composer-${{ steps.key-date.outputs.date }}-${{ hashFiles('composer.json') }}-${{ matrix.prefer-lowest }}
+
+      - name: Composer install
+        run: |
+          if [[ ${{ matrix.php-version }} == '8.0' ]]; then
+            composer install --ignore-platform-reqs
+          elif ${{ matrix.prefer-lowest == 'prefer-lowest' }}; then
+            composer update --prefer-lowest --prefer-stable
+          else
+            composer install
+          fi
+
+      - name: Run PHPUnit
+        run: |
+          if [[ ${{ matrix.php-version }} == '7.4' ]]; then
+            vendor/bin/phpunit --coverage-clover=coverage.xml
+          else
+            vendor/bin/phpunit
+          fi
+
+      - name: Code Coverage Report
+        if: success() && matrix.php-version == '7.4'
+        uses: codecov/codecov-action@v1
 
   validation:
     name: Coding Standard & Static Analysis
     runs-on: ubuntu-18.04
 
     steps:
-    - uses: actions/checkout@v2
-      with:
-        fetch-depth: 1
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 1
 
-    - name: Setup PHP
-      uses: shivammathur/setup-php@v2
-      with:
-        php-version: '7.4'
-        extensions: mbstring, intl
-        coverage: none
-        tools: psalm:~4.1.0
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '7.4'
+          extensions: mbstring, intl
+          coverage: none
+          tools: psalm:~4.1.0
 
-    - name: Composer Install
-      run: composer stan-setup
+      - name: Composer Install
+        run: composer stan-setup
 
-    - name: Run phpstan
-      run: composer phpstan
+      - name: Run phpstan
+        run: composer phpstan
 
-    - name: Run phpcs
-      run: composer cs-check
+      - name: Run phpcs
+        run: composer cs-check
 
     # - name: Run psalm
-    #   run: psalm --output-format=github
\ No newline at end of file
+    #   run: psalm --output-format=github
diff --git a/README.md b/README.md
index 261a753..3e2bfa5 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,14 @@
 
 This plugin provides email delivery using [SendGrid](https://sendgrid.com/).
 
-This branch is for use with CakePHP 5.0+. For CakePHP 4, please use cake-4.x branch.
+This branch is for use with **CakePHP 5.0+**. For other versions of CakePHP, please use the following version map.
+
+
+| SendGrid Plugin | Branch | CakePHP Core|
+| --- | --- | --- |
+| 1.x **[EOL]** | [cake-3.x](https://github.com/sprintcube/cakephp-sendgrid/tree/cake-3.x) | 3.4+ |
+| 4.x | [cake-4.x](https://github.com/sprintcube/cakephp-sendgrid/tree/cake-4.x) | 4.0+ |
+| 5.x (in progress) | [master](https://github.com/sprintcube/cakephp-sendgrid/tree/master) | 5.0+ |
 
 ## Requirements
 
@@ -171,7 +178,7 @@ You will need to login to your SendGrid Account and configure your domain and th
  https://app.sendgrid.com/settings/mail_settings/webhook_settings
 
 The return url needs to be set to 
-* https://YOUR DOMAIN/send-grid/webhook
+* https://YOURDOMAIN/send-grid/webhook
 
 
 The CSRF protection middleware needs to allow posts to the webhooks controller in Application.php
diff --git a/src/Controller/AppController.php b/src/Controller/AppController.php
index 5803c41..cac3c3e 100644
--- a/src/Controller/AppController.php
+++ b/src/Controller/AppController.php
@@ -1,10 +1,23 @@
 <?php
+
 declare(strict_types=1);
 
+/**
+ * SendGrid Plugin for CakePHP
+ * Copyright (c) SprintCube (https://www.sprintcube.com)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.md
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright Copyright (c) SprintCube (https://www.sprintcube.com)
+ * @license   https://opensource.org/licenses/mit-license.php MIT License
+ * @link      https://github.com/sprintcube/cakephp-sendgrid
+ * @since     5.0.0
+ */
+
 namespace SendGrid\Controller;
 
 use App\Controller\AppController as BaseController;
 
-class AppController extends BaseController
-{
-}
+class AppController extends BaseController {}
diff --git a/src/Controller/WebhooksController.php b/src/Controller/WebhooksController.php
index 3567576..9e6b176 100644
--- a/src/Controller/WebhooksController.php
+++ b/src/Controller/WebhooksController.php
@@ -19,6 +19,19 @@
  * 
  */
 
+/**
+ * SendGrid Plugin for CakePHP
+ * Copyright (c) SprintCube (https://www.sprintcube.com)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.md
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright Copyright (c) SprintCube (https://www.sprintcube.com)
+ * @license   https://opensource.org/licenses/mit-license.php MIT License
+ * @link      https://github.com/sprintcube/cakephp-sendgrid
+ * @since     5.0.0
+ */
 
 namespace SendGrid\Controller;
 
@@ -75,7 +88,7 @@ public function index()
         if (isset($config['secure']) && $config['secure'] == 'true') {
             $this->request->getBody()->rewind();
             $payload = $this->request->getBody()->getContents();
-           // Log::debug($payload);
+            // Log::debug($payload);
 
             if (!isset($config['verification_key'])) {
                 if (isset($config['debug']) && $config['debug'] == 'true') {
@@ -85,7 +98,7 @@ public function index()
                 $this->viewBuilder()->setOption('serialize', "error");
                 return;
             }
-            
+
             $publicKey = PublicKey::fromString($config['verification_key']);
 
             $timestampedPayload = $this->request->getHeaderLine($this::TIMESTAMP) . $payload;
@@ -126,5 +139,4 @@ public function index()
         $this->set('OK', "OK");
         $this->viewBuilder()->setOption('serialize', "OK");
     }
-
 }
diff --git a/src/Mailer/SendGridMailer.php b/src/Mailer/SendGridMailer.php
index 14c3830..e33b283 100644
--- a/src/Mailer/SendGridMailer.php
+++ b/src/Mailer/SendGridMailer.php
@@ -1,4 +1,5 @@
 <?php
+
 declare(strict_types=1);
 
 /**
diff --git a/src/Mailer/Transport/SendGridTransport.php b/src/Mailer/Transport/SendGridTransport.php
index dc59264..5add671 100644
--- a/src/Mailer/Transport/SendGridTransport.php
+++ b/src/Mailer/Transport/SendGridTransport.php
@@ -193,10 +193,9 @@ protected function _prepareEmailAddresses(Message $message)
         if (!empty($replyTo)) {
             if (key($replyTo) != $replyTo[key($replyTo)]) {
                 $this->_reqParams['reply_to'] = (object)['email' => key($replyTo), 'name' => $replyTo[key($replyTo)]];
-                
             } else {
                 $this->_reqParams['reply_to'] = (object)['email' => key($replyTo)];
-            }        
+            }
         }
 
         $emails = [];
@@ -207,6 +206,10 @@ protected function _prepareEmailAddresses(Message $message)
             ];
         }
 
+        if (empty($emails['to'])) {
+            throw new SendGridApiException('Missing to email address.');
+        }
+
         foreach ($message->getCc() as $ccEmail => $ccName) {
             $emails['cc'][] = [
                 'email' => $ccEmail,