diff --git a/README.md b/README.md
index f603daf..a0a028d 100644
--- a/README.md
+++ b/README.md
@@ -14,13 +14,13 @@ A **self-hosted** disposable mailbox  service (aka trash mail)  :cloud: :envelop
 * Automatic refresh. Download and delete your emails.
 * Display emails as text or html with sanitization  filter. 
 * Display emails based on one [catch-all imap mailbox](https://www.google.ch/search?q=how+to+setup+catch-all+imap+mailbox).
-* Only requires PHP  >=5.3.0 and [imap extension](http://php.net/manual/book.imap.php)
+* Only requires PHP  >=7.2 and [imap extension](http://php.net/manual/book.imap.php)
 
 ## Usage
 
 ### Requirements
 
-* webserver with php >=5.3.0
+* webserver with php >=7.2
 * php [imap extension](http://php.net/manual/book.imap.php)
 * IMAP account and a domain with [catch-all configuration](https://www.google.ch/search?q=how+to+setup+catch-all+imap+mailbox). (all emails go to one mailbox). 
 
diff --git a/src/autolink.php b/src/autolink.php
new file mode 100644
index 0000000..d9ea250
--- /dev/null
+++ b/src/autolink.php
@@ -0,0 +1,49 @@
+<?php
+
+class AutoLinkExtension {
+    static public function auto_link_text($string) {
+
+        $string = preg_replace_callback("/
+            ((?<![\"'])                                     # don't look inside quotes
+            (\b
+            (                           # protocol or www.
+                [a-z]{3,}:\/\/
+            |
+                www\.
+            )
+            (?:                         # domain
+                [a-zA-Z0-9_\-]+
+                (?:\.[a-zA-Z0-9_\-]+)*
+            |
+                localhost
+            )
+            (?:                         # port
+                 \:[0-9]+
+            )?
+            (?:                         # path
+                \/[a-z0-9:%_|~.-]*
+                (?:\/[a-z0-9:%_|~.-]*)*
+            )?
+            (?:                         # attributes
+                \?[a-z0-9:%_|~.=&#;-]*
+            )?
+            (?:                         # anchor
+                \#[a-z0-9:%_|~.=&#;-]*
+            )?
+            )
+            (?![\"']))
+            /ix",
+            function ($match) {
+                $url = $match[0];
+                $href = $url;
+
+                if (false === strpos($href, 'http')) {
+                    $href = 'http://' . $href;
+                }
+                return '<a href="' . $href . '" rel="noreferrer">' . $url . '</a>';
+            }, $string);
+
+        return $string;
+    }
+
+}
diff --git a/src/frontend.template.php b/src/frontend.template.php
index 16c40e9..4a1e56a 100644
--- a/src/frontend.template.php
+++ b/src/frontend.template.php
@@ -88,7 +88,7 @@ $purifier = new HTMLPurifier($purifier_config);
             mailbox:
         </small>
 
-        <form id="header-form" data-turbolinks-permanent action="?" method="post">
+        <form id="header-form" data-turbolinks-permanent action="?action=redirect" method="post">
             <div class="form-group row">
 
                 <div class="col-lg-5 col-md-4 col-sm-6 col-xs-12">
@@ -117,7 +117,7 @@ $purifier = new HTMLPurifier($purifier_config);
                     ?>
                 </div>
                 <div class="col-lg-3 col-md-4 col-sm-12 col-xs-12 random-column">
-                    <a role="button" href="?random=true"
+                    <a role="button" href="?action=random"
                        class="btn btn-outline-primary col-sm-12 col-xs-12 random-button">Generate
                         Random</a>
                 </div>
@@ -177,12 +177,12 @@ $purifier = new HTMLPurifier($purifier_config);
                                 <div class="col-sm-4 text-right">
                                     <a class="btn btn-sm btn-outline-primary " download="true"
                                        role="button"
-                                       href="?download_email_id=<?php echo $safe_email_id; ?>&amp;address=<?php echo $user->address ?>">Download
+                                       href="?action=download_email&download_email_id=<?php echo $safe_email_id; ?>&amp;address=<?php echo $user->address ?>">Download
                                     </a>
 
                                     <a class="btn btn-sm btn-outline-danger"
                                        role="button"
-                                       href="?delete_email_id=<?php echo $safe_email_id; ?>&amp;address=<?php echo $user->address ?>">Delete
+                                       href="?action=delete_email&delete_email_id=<?php echo $safe_email_id; ?>&amp;address=<?php echo $user->address ?>">Delete
                                     </a>
                                 </div>
                             </div>
diff --git a/src/index.php b/src/index.php
index a1d280c..6373137 100644
--- a/src/index.php
+++ b/src/index.php
@@ -9,48 +9,17 @@ $mailbox = new PhpImap\Mailbox($config['imap']['url'],
     $config['imap']['username'],
     $config['imap']['password']);
 
+require_once './user.php';
+require_once './autolink.php';
+require_once './pages.php';
+require_once './router.php';
 
-// simple router:
-if (isset($_POST['username']) && isset($_POST['domain'])) {
-    $user = User::parseUsernameAndDomain($_POST['username'], $_POST['domain']);
-    header("location: ?" . $user->username . "@" . $user->domain);
-    exit();
-} elseif (isset($_GET['download_email_id']) && isset($_GET['address'])) {
-    $user = User::parseDomain($_GET['address']);
-    $download_email_id = filter_input(INPUT_GET, 'download_email_id', FILTER_SANITIZE_NUMBER_INT);
-    if ($user->isInvalid()) {
-        redirect_to_random($config['domains']);
-        exit();
-    }
-    download_email($download_email_id, $user);
-    exit();
-} elseif (isset($_GET['delete_email_id']) && isset($_GET['address'])) {
-    $user = User::parseDomain($_GET['address']);
-    $delete_email_id = filter_input(INPUT_GET, 'delete_email_id', FILTER_SANITIZE_NUMBER_INT);
-    if ($user->isInvalid()) {
-        redirect_to_random($config['domains']);
-        exit();
-    }
-    delete_email($delete_email_id, $user);
-    header("location: ?" . $user->address);
-    exit();
-} elseif (isset($_GET['random'])) {
-    redirect_to_random($config['domains']);
-    exit();
-} else {
-    // print emails with html template
-    $user = User::parseDomain($_SERVER['QUERY_STRING']);
-    if ($user->isInvalid()) {
-        redirect_to_random($config['domains']);
-        exit();
-    }
-    $emails = get_emails($user);
-    require "frontend.template.php";
-
-    // delete after each request
-    delete_old_messages();
-}
+$router = new Router($_SERVER['REQUEST_METHOD'], $_GET['action'] ?? NULL, $_GET, $_POST, $_SERVER['QUERY_STRING'], $config);
+$page = $router->route();
+$page->invoke();
 
+// delete after each request
+delete_old_messages();
 
 /**
  * print error and stop program.
@@ -184,40 +153,6 @@ function _clean_username($address) {
     return $username;
 }
 
-class User {
-    public $address;
-    public $username;
-    public $domain;
-
-    public function isInvalid() {
-        global $config;
-        if (empty($this->username) || empty($this->domain)) {
-            return true;
-        } else if (!in_array($this->domain, $config['domains'])) {
-            return true;
-        } else {
-            return false;
-        }
-    }
-
-    public static function parseDomain($address) {
-        $clean_address = _clean_address($address);
-        $user = new User();
-        $user->username = _clean_username($clean_address);
-        $user->domain = _clean_domain($clean_address);
-        $user->address = $user->username . '@' . $user->domain;
-        return $user;
-    }
-
-    public static function parseUsernameAndDomain($username, $domain) {
-        $user = new User();
-        $user->username = _clean_username($username);
-        $user->domain = _clean_domain($domain);
-        $user->address = $user->username . '@' . $user->domain;
-        return $user;
-    }
-}
-
 
 function _clean_domain($address) {
     $username = strtolower($address);
@@ -225,7 +160,7 @@ function _clean_domain($address) {
     return preg_replace('/[^A-Za-z0-9_.+-]/', "", $username);   // remove special characters
 }
 
-function redirect_to_random($domains) {
+function redirect_to_random(array $domains) {
     $wordLength = rand(3, 8);
     $container = new PronounceableWord_DependencyInjectionContainer();
     $generator = $container->getGenerator();
@@ -251,52 +186,4 @@ function delete_old_messages() {
 }
 
 
-class AutoLinkExtension {
-    static public function auto_link_text($string) {
-
-        $string = preg_replace_callback("/
-            ((?<![\"'])                                     # don't look inside quotes
-            (\b
-            (                           # protocol or www.
-                [a-z]{3,}:\/\/
-            |
-                www\.
-            )
-            (?:                         # domain
-                [a-zA-Z0-9_\-]+
-                (?:\.[a-zA-Z0-9_\-]+)*
-            |
-                localhost
-            )
-            (?:                         # port
-                 \:[0-9]+
-            )?
-            (?:                         # path
-                \/[a-z0-9:%_|~.-]*
-                (?:\/[a-z0-9:%_|~.-]*)*
-            )?
-            (?:                         # attributes
-                \?[a-z0-9:%_|~.=&#;-]*
-            )?
-            (?:                         # anchor
-                \#[a-z0-9:%_|~.=&#;-]*
-            )?
-            )
-            (?![\"']))
-            /ix",
-            function ($match) {
-                $url = $match[0];
-                $href = $url;
-
-                if (false === strpos($href, 'http')) {
-                    $href = 'http://' . $href;
-                }
-                return '<a href="' . $href . '" rel="noreferrer">' . $url . '</a>';
-            }, $string);
-
-        return $string;
-    }
-
-}
-
 ?>
\ No newline at end of file
diff --git a/src/pages.php b/src/pages.php
new file mode 100644
index 0000000..aa5925b
--- /dev/null
+++ b/src/pages.php
@@ -0,0 +1,114 @@
+<?php
+
+abstract class Page {
+
+    function invoke() {
+    }
+
+    function if_invalid_redirect_to_random(User $user, array $config_domains) {
+        if ($user->isInvalid()) {
+            redirect_to_random($config_domains);
+            exit();
+        }
+    }
+}
+
+class RedirectToAddressPage extends Page {
+    private $username;
+    private $domain;
+
+    public function __construct(string $username, string $domain) {
+        $this->username = $username;
+        $this->domain = $domain;
+    }
+
+    function invoke() {
+        $user = User::parseUsernameAndDomain($this->username, $this->domain);
+        header("location: ?" . $user->username . "@" . $user->domain);
+    }
+}
+
+class DownloadEmailPage extends Page {
+
+    private $email_id;
+    private $address;
+    private $config_domains;
+
+    public function __construct(string $email_id, string $address, array $config_domains) {
+        $this->email_id = $email_id;
+        $this->address = $address;
+        $this->config_domains = $config_domains;
+    }
+
+
+    function invoke() {
+        $user = User::parseDomain($this->address);
+        $this->if_invalid_redirect_to_random($user, $this->config_domains);
+
+        $download_email_id = filter_var($this->email_id, FILTER_SANITIZE_NUMBER_INT);
+        download_email($download_email_id, $user);
+    }
+}
+
+
+class DeleteEmailPage extends Page {
+    private $email_id;
+    private $address;
+    private $config_domains;
+
+    public function __construct($email_id, $address, $config_domains) {
+        $this->email_id = $email_id;
+        $this->address = $address;
+        $this->config_domains = $config_domains;
+    }
+
+    function invoke() {
+        $user = User::parseDomain($this->address);
+        $this->if_invalid_redirect_to_random($user, $this->config_domains);
+
+        $delete_email_id = filter_var($this->email_id, FILTER_SANITIZE_NUMBER_INT);
+        delete_email($delete_email_id, $user);
+        header("location: ?" . $user->address);
+    }
+}
+
+class RedirectToRandomAddressPage extends Page {
+    private $config_domains;
+
+    public function __construct($config_domains) {
+        $this->config_domains = $config_domains;
+    }
+
+    function invoke() {
+        redirect_to_random($this->config_domains);
+    }
+
+}
+
+class DisplayEmailsPage extends Page {
+    private $address;
+    private $config;
+
+    public function __construct($address, $config) {
+        $this->address = $address;
+        $this->config = $config;
+    }
+
+
+    function invoke() {
+        // print emails with html template
+        $user = User::parseDomain($this->address);
+        $this->if_invalid_redirect_to_random($user, $this->config['domains']);
+
+        global $emails;
+        global $config;
+        $emails = get_emails($user);
+        require "frontend.template.php";
+    }
+}
+
+class InvalidRequestPage extends Page {
+    function invoke() {
+        error(400, "Bad Request");
+    }
+}
diff --git a/src/router.php b/src/router.php
new file mode 100644
index 0000000..39db024
--- /dev/null
+++ b/src/router.php
@@ -0,0 +1,54 @@
+<?php
+
+require_once './pages.php';
+
+class Router {
+
+    private $method;
+    private $action;
+    private $get_vars;
+    private $post_vars;
+    private $query_string;
+    private $config;
+
+    public function __construct(string $method, string $action = NULL, array $get_vars, array $post_vars, string $query_string, array $config) {
+        $this->method = $method;
+        $this->action = $action;
+        $this->get_vars = $get_vars;
+        $this->post_vars = $post_vars;
+        $this->query_string = $query_string;
+        $this->config = $config;
+    }
+
+
+    function route(): Page {
+        if ($this->action === "redirect"
+            && isset($this->post_vars['username'])
+            && isset($this->post_vars['domain'])) {
+            return new RedirectToAddressPage($this->post_vars['username'], $this->post_vars['domain']);
+
+        } elseif ($this->action === "download_email"
+            && isset($this->get_vars['download_email_id'])
+            && isset($this->get_vars['address'])) {
+            return new DownloadEmailPage($this->get_vars['download_email_id'], $this->get_vars['address'], $this->config['domains']);
+
+        } elseif ($this->action === "delete_email"
+            && isset($this->get_vars['delete_email_id'])
+            && isset($this->get_vars['address'])) {
+            return new DeleteEmailPage($this->get_vars['delete_email_id'], $this->get_vars['address'], $this->config['domains']);
+
+        } elseif ($this->action === 'random') {
+            return new RedirectToRandomAddressPage($this->config['domains']);
+
+        } elseif (empty($this->query_string)) {
+            return new RedirectToRandomAddressPage($this->config['domains']);
+
+        } elseif (!empty($this->query_string)) {
+            return new DisplayEmailsPage($this->query_string, $this->config);
+
+        } else {
+            return new InvalidRequestPage();
+
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/user.php b/src/user.php
new file mode 100644
index 0000000..2791c55
--- /dev/null
+++ b/src/user.php
@@ -0,0 +1,35 @@
+<?php
+
+class User {
+    public $address;
+    public $username;
+    public $domain;
+
+    public function isInvalid(): bool {
+        global $config;
+        if (empty($this->username) || empty($this->domain)) {
+            return true;
+        } else if (!in_array($this->domain, $config['domains'])) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    public static function parseDomain(string $address): User {
+        $clean_address = _clean_address($address);
+        $user = new User();
+        $user->username = _clean_username($clean_address);
+        $user->domain = _clean_domain($clean_address);
+        $user->address = $user->username . '@' . $user->domain;
+        return $user;
+    }
+
+    public static function parseUsernameAndDomain(string $username, string $domain): User {
+        $user = new User();
+        $user->username = _clean_username($username);
+        $user->domain = _clean_domain($domain);
+        $user->address = $user->username . '@' . $user->domain;
+        return $user;
+    }
+}