diff --git a/securemail/securemail.php b/securemail/securemail.php
index c4dc6c93c..b5275e08f 100644
--- a/securemail/securemail.php
+++ b/securemail/securemail.php
@@ -6,88 +6,104 @@
  * Author: Fabio Comuni <http://kirgroup.com/profile/fabrixxm>
  */
 
-require_once "include/Emailer.php";
+require_once 'include/Emailer.php';
 
 /* because the fraking openpgp-php is in composer, require libs in composer
  * and then don't use autoloader to load classes... */
-$path = __DIR__."/vendor/phpseclib/phpseclib/phpseclib/";
+$path = __DIR__ . '/vendor/phpseclib/phpseclib/phpseclib/';
 set_include_path(get_include_path() . PATH_SEPARATOR . $path);
 /* so, we don't use the autoloader and include what we need */
-$path = __DIR__."/vendor/singpolyma/openpgp-php/lib";
+$path = __DIR__ . '/vendor/singpolyma/openpgp-php/lib';
 set_include_path(get_include_path() . PATH_SEPARATOR . $path);
 
-require_once "openpgp.php";
-require_once "openpgp_crypt_symmetric.php";
+require_once 'openpgp.php';
+require_once 'openpgp_crypt_symmetric.php';
 
 
 function securemail_install() {
     register_hook('plugin_settings', 'addon/securemail/securemail.php', 'securemail_settings');
     register_hook('plugin_settings_post', 'addon/securemail/securemail.php', 'securemail_settings_post');
 
-    register_hook('emailer_send_prepare',  'addon/securemail/securemail.php', 'securemail_emailer_send_prepare');
+    register_hook('emailer_send_prepare', 'addon/securemail/securemail.php', 'securemail_emailer_send_prepare');
 
-    logger("installed securemail");
+    logger('installed securemail');
 }
 
 function securemail_uninstall() {
     unregister_hook('plugin_settings', 'addon/securemail/securemail.php', 'securemail_settings');
     unregister_hook('plugin_settings_post', 'addon/securemail/securemail.php', 'securemail_settings_post');
 
-    unregister_hook('emailer_send_prepare',  'addon/securemail/securemail.php', 'securemail_emailer_send_prepare');
+    unregister_hook('emailer_send_prepare', 'addon/securemail/securemail.php', 'securemail_emailer_send_prepare');
 
-    logger("removed securemail");
+    logger('removed securemail');
 }
 
-
-function securemail_settings(&$a,&$s){
-    if(! local_user()) {
+/**
+ * @brief Build user settings form
+ *
+ * @link https://github.com/friendica/friendica/blob/develop/doc/Plugins.md#plugin_settings 'plugin_settings' hook
+ *
+ * @param App $a App instance
+ * @param string $s output html
+ *
+ * @see App
+ */
+function securemail_settings(App &$a, string &$s){
+    if (!local_user()) {
         return;
     }
 
-    $enable = intval(get_pconfig(local_user(),'securemail','enable'));
-    $publickey = get_pconfig(local_user(),'securemail','pkey');
+    $enable = intval(get_pconfig(local_user(), 'securemail', 'enable'));
+    $publickey = get_pconfig(local_user(), 'securemail', 'pkey');
 
-    $t = get_markup_template( "admin.tpl", "addon/securemail/" );
+    $t = get_markup_template('admin.tpl', 'addon/securemail/');
 
     $s = replace_macros($t, array(
         '$title' => t('"Secure Mail" Settings'),
         '$submit' => t('Save Settings'),
         '$test' => t('Save and send test'), //NOTE: update also in 'post'
-        '$enable' => array('securemail-enable', t('Enable Secure Mail'), $enable, ""),
-        '$publickey' => array('securemail-pkey', t('Public key'), $publickey, t("Your public PGP key, ascii armored format"), "rows='10'")
+        '$enable' => array('securemail-enable', t('Enable Secure Mail'), $enable, ''),
+        '$publickey' => array('securemail-pkey', t('Public key'), $publickey, t('Your public PGP key, ascii armored format'), 'rows="10"')
     ));
-
-
-
-    return;
 }
-function securemail_settings_post(&$a, &$b){
 
-    if(! local_user()) {
+/**
+ * @brief Handle data from user settings form
+ *
+ * @link https://github.com/friendica/friendica/blob/develop/doc/Plugins.md#plugin_settings_post 'plugin_settings_post' hook
+ *
+ * @param App $a App instance
+ * @param array $b hook data
+ *
+ * @see App
+ */
+function securemail_settings_post(App &$a, array &$b){
+
+    if (!local_user()) {
         return;
     }
 
-    if($_POST['securemail-submit']) {
-        set_pconfig(local_user(),'securemail','pkey',trim($_POST['securemail-pkey']));
-        $enable = ((x($_POST,'securemail-enable')) ? 1 : 0);
-        set_pconfig(local_user(),'securemail','enable', $enable);
-        info( t('Secure Mail Settings saved.') . EOL);
+    if ($_POST['securemail-submit']) {
+        set_pconfig(local_user(), 'securemail', 'pkey', trim($_POST['securemail-pkey']));
+        $enable = ((x($_POST, 'securemail-enable')) ? 1 : 0);
+        set_pconfig(local_user(), 'securemail', 'enable', $enable);
+        info(t('Secure Mail Settings saved.') . EOL);
 
         if ($_POST['securemail-submit'] == t('Save and send test')) {
             $sitename = $a->config['sitename'];
 
             $hostname = $a->get_hostname();
-            if (strpos($hostname, ':')){
+            if (strpos($hostname, ':')) {
                 $hostname = substr($hostname, 0, strpos($hostname, ':'));
             }
 
             $sender_email = $a->config['sender_email'];
-            if (empty($sender_email)){
-                $sender_email = 'noreply@'.$hostname;
+            if (empty($sender_email)) {
+                $sender_email = 'noreply@' . $hostname;
             }
 
-            $subject = "Friendica - Secure Mail - Test";
-            $message = "This is a test message from your Friendica Secure Mail addon.\n\nBye!";
+            $subject = 'Friendica - Secure Mail - Test';
+            $message = 'This is a test message from your Friendica Secure Mail addon.\n\nBye!';
 
             $params = array(
                 'uid' => local_user(),
@@ -100,35 +116,45 @@ function securemail_settings_post(&$a, &$b){
             );
 
             // enable addon for test
-            set_pconfig(local_user(),'securemail','enable', 1);
+            set_pconfig(local_user(), 'securemail', 'enable', 1);
 
             $res = Emailer::send($params);
 
             // revert to saved value
-            set_pconfig(local_user(),'securemail','enable', $enable);
+            set_pconfig(local_user(), 'securemail', 'enable', $enable);
 
             if ($res) {
-                info( t("Test email sent") . EOL);
+                info(t('Test email sent') . EOL);
             } else {
-                notice( t("There was an error sending the test email") .EOL);
+                notice(t('There was an error sending the test email') . EOL);
             }
         }
     }
 }
 
-function securemail_emailer_send_prepare(&$a, &$b) {
+/**
+ * @brief Encrypt notification emails text
+ *
+ * @link https://github.com/friendica/friendica/blob/develop/doc/Plugins.md#emailer_send_prepare 'emailer_send_prepare' hook
+ *
+ * @param App $a App instance
+ * @param array $b hook data
+ *
+ * @see App
+ */
+function securemail_emailer_send_prepare(App &$a, array &$b) {
     if (!x($b,'uid')) {
         return;
     }
 
     $uid = $b['uid'];
 
-    $enable_checked = get_pconfig($uid,'securemail','enable');
+    $enable_checked = get_pconfig($uid, 'securemail', 'enable');
     if (!$enable_checked) {
         return;
     }
 
-    $public_key_ascii = get_pconfig($uid,'securemail','pkey');
+    $public_key_ascii = get_pconfig($uid, 'securemail', 'pkey');
 
     preg_match('/-----BEGIN ([A-Za-z ]+)-----/', $public_key_ascii, $matches);
     $marker = (empty($matches[1])) ? 'MESSAGE' : $matches[1];
@@ -141,7 +167,12 @@ function securemail_emailer_send_prepare(&$a, &$b) {
         'filename' => 'encrypted.gpg'
     ));
     $encrypted = OpenPGP_Crypt_Symmetric::encrypt($key, new OpenPGP_Message(array($data)));
-    $armored_encrypted = wordwrap(OpenPGP::enarmor($encrypted->to_bytes(), "PGP MESSAGE"), 64, "\n", true);
+    $armored_encrypted = wordwrap(
+        OpenPGP::enarmor($encrypted->to_bytes(), 'PGP MESSAGE'),
+        64,
+        '\n',
+        true
+    );
 
     $b['textVersion'] = $armored_encrypted;
     $b['htmlVersion'] = null;
@@ -153,7 +184,7 @@ function securemail_emailer_send_prepare(&$a, &$b) {
 
 function securemail_autoloader() {
 
-    $loader = require dirname(dirname(__DIR__))."/vendor/autoload.php";
+    $loader = require dirname(dirname(__DIR__)) . '/vendor/autoload.php';
 
     $map = require __DIR__ . '/vendor/composer/autoload_namespaces.php';
     foreach ($map as $namespace => $path) {