diff --git a/CHANGELOG b/CHANGELOG
index d1958b1b3..da091e7d9 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Enigma: Added option to attach public keys to sent mail (#5152)
 - Enigma: Handle messages with text before an encrypted block (#5149)
 - Enigma: Handle encrypted/signed content inside message/rfc822 attachments
 - Enigma: Fix missing html/plain switch on multipart/signed messages (#1490649)
@@ -30,6 +31,7 @@ CHANGELOG Roundcube Webmail
 - Protect download urls against CSRF using unique request tokens (#1490642)
 - newmail_notifier: Refactor desktop notifications
 - Fix so contactlist_fields option can be set via config file
+- Fix so SPECIAL-USE assignments are forced only until user sets special folders (#4782)
 
 RELEASE 1.2-beta
 ----------------
diff --git a/plugins/acl/acl.php b/plugins/acl/acl.php
index 8058656f6..6a0468154 100644
--- a/plugins/acl/acl.php
+++ b/plugins/acl/acl.php
@@ -563,7 +563,7 @@ class acl extends rcube_plugin
 
         $this->mbox = trim(rcube_utils::get_input_value('_mbox', rcube_utils::INPUT_GPC, true)); // UTF7-IMAP
         $advanced   = trim(rcube_utils::get_input_value('_mode', rcube_utils::INPUT_GPC));
-        $advanced   = $advanced == 'advanced' ? true : false;
+        $advanced   = $advanced == 'advanced';
 
         // Save state in user preferences
         $this->rc->user->save_prefs(array('acl_advanced_mode' => $advanced));
diff --git a/plugins/emoticons/emoticons.php b/plugins/emoticons/emoticons.php
index d5f0e9a16..5de5f91e9 100644
--- a/plugins/emoticons/emoticons.php
+++ b/plugins/emoticons/emoticons.php
@@ -175,10 +175,10 @@ class emoticons extends rcube_plugin
         $dont_override = $rcube->config->get('dont_override', array());
 
         if ($args['section'] == 'mailview' && !in_array('emoticons_display', $dont_override)) {
-            $args['prefs']['emoticons_display'] = rcube_utils::get_input_value('_emoticons_display', rcube_utils::INPUT_POST) ? true : false;
+            $args['prefs']['emoticons_display'] = !empty(rcube_utils::get_input_value('_emoticons_display', rcube_utils::INPUT_POST));
         }
         else if ($args['section'] == 'compose' && !in_array('emoticons_compose', $dont_override)) {
-            $args['prefs']['emoticons_compose'] = rcube_utils::get_input_value('_emoticons_compose', rcube_utils::INPUT_POST) ? true : false;
+            $args['prefs']['emoticons_compose'] = !empty(rcube_utils::get_input_value('_emoticons_compose', rcube_utils::INPUT_POST));
         }
 
         return $args;
diff --git a/plugins/enigma/README b/plugins/enigma/README
index ac20b790a..d9fc3799b 100644
--- a/plugins/enigma/README
+++ b/plugins/enigma/README
@@ -18,6 +18,7 @@ Implemented features:
 + PGP: key generation (client- or server-side)
 + Handling of PGP keys attached to incoming messages
 + User preferences to disable plugin features
++ Attaching public keys to email
 
 
 TODO:
@@ -33,7 +34,6 @@ TODO:
 - Generate revocation certs
 - Search filter to see invalid/expired keys
 - Key server(s) support (search, import, upload, refresh)
-- Attaching public keys to email
 - Mark keys as trusted/untrasted, display appropriate message in verify/decrypt status
 - Change attachment icon on messages list for encrypted messages (like vcard_attachment plugin does)
 - Support for multi-server installations (store keys in sql database?)
diff --git a/plugins/enigma/composer.json b/plugins/enigma/composer.json
index 3245ee7b3..4cfc44d54 100644
--- a/plugins/enigma/composer.json
+++ b/plugins/enigma/composer.json
@@ -3,7 +3,7 @@
     "type": "roundcube-plugin",
     "description": "PGP Encryption for Roundcube",
     "license": "GPLv3+",
-    "version": "0.4",
+    "version": "0.5",
     "authors": [
         {
             "name": "Aleksander Machniak",
@@ -23,7 +23,7 @@
     ],
     "require": {
         "php": ">=5.3.0",
-        "roundcube/plugin-installer": ">=0.1.3",
-        "pear-pear.php.net/crypt_gpg": "*"
+        "roundcube/plugin-installer": "~0.1.6",
+        "pear-pear.php.net/crypt_gpg": "~1.4.0"
     }
 }
diff --git a/plugins/enigma/config.inc.php.dist b/plugins/enigma/config.inc.php.dist
index 17e3265b6..2cce5ee95 100644
--- a/plugins/enigma/config.inc.php.dist
+++ b/plugins/enigma/config.inc.php.dist
@@ -28,6 +28,9 @@ $config['enigma_sign_all'] = false;
 // Enable encrypting all messages by default
 $config['enigma_encrypt_all'] = false;
 
+// Enable attaching a public key to all messages by default
+$config['enigma_attach_pubkey'] = false;
+
 // Default for how long to store private key passwords (in minutes).
 // When set to 0 passwords will be stored for the whole session.
 $config['enigma_password_time'] = 5;
diff --git a/plugins/enigma/enigma.php b/plugins/enigma/enigma.php
index 8e8ded2a1..2ebe2cc66 100644
--- a/plugins/enigma/enigma.php
+++ b/plugins/enigma/enigma.php
@@ -339,6 +339,25 @@ class enigma extends rcube_plugin
             );
         }
 
+        if (!isset($no_override['enigma_attach_pubkey'])) {
+            if (!$p['current']) {
+                $p['blocks']['main']['content'] = true;
+                return $p;
+            }
+
+            $field_id = 'rcmfd_enigma_attach_pubkey';
+            $input    = new html_checkbox(array(
+                    'name'  => '_enigma_attach_pubkey',
+                    'id'    => $field_id,
+                    'value' => 1,
+            ));
+
+            $p['blocks']['main']['options']['enigma_attach_pubkey'] = array(
+                'title'   => html::label($field_id, $this->gettext('attachpubkeydefault')),
+                'content' => $input->show($this->rc->config->get('enigma_attach_pubkey') ? 1 : 0),
+            );
+        }
+
         if (!isset($no_override['enigma_password_time'])) {
             if (!$p['current']) {
                 $p['blocks']['main']['content'] = true;
@@ -380,6 +399,7 @@ class enigma extends rcube_plugin
                 'enigma_encryption'    => (bool) rcube_utils::get_input_value('_enigma_encryption', rcube_utils::INPUT_POST),
                 'enigma_sign_all'      => (bool) rcube_utils::get_input_value('_enigma_sign_all', rcube_utils::INPUT_POST),
                 'enigma_encrypt_all'   => (bool) rcube_utils::get_input_value('_enigma_encrypt_all', rcube_utils::INPUT_POST),
+                'enigma_attach_pubkey' => (bool) rcube_utils::get_input_value('_enigma_attach_pubkey', rcube_utils::INPUT_POST),
                 'enigma_password_time' => intval(rcube_utils::get_input_value('_enigma_password_time', rcube_utils::INPUT_POST)),
             );
         }
diff --git a/plugins/enigma/lib/enigma_engine.php b/plugins/enigma/lib/enigma_engine.php
index 96f792d90..c97093329 100644
--- a/plugins/enigma/lib/enigma_engine.php
+++ b/plugins/enigma/lib/enigma_engine.php
@@ -312,6 +312,33 @@ class enigma_engine
         }
     }
 
+    /**
+     * Handler for attaching public key to a message
+     *
+     * @param Mail_mime Original message
+     *
+     * @return bool True on success, False on failure
+     */
+    function attach_public_key(&$message)
+    {
+        $headers = $message->headers();
+        $from    = rcube_mime::decode_address_list($headers['From'], 1, false, null, true);
+        $from    = $from[1];
+
+        // find my key
+        if ($from && ($key = $this->find_key($from))) {
+            $pubkey_armor = $this->export_key($key->id);
+
+            if (!$pubkey_armor instanceof enigma_error) {
+                $pubkey_name = '0x' . enigma_key::format_id($key->id) . '.asc';
+                $message->addAttachment($pubkey_armor, 'application/pgp-keys', $pubkey_name, false, '7bit');
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * Handler for message_part_structure hook.
      * Called for every part of the message.
diff --git a/plugins/enigma/lib/enigma_ui.php b/plugins/enigma/lib/enigma_ui.php
index 6ae69daff..37c1d414a 100644
--- a/plugins/enigma/lib/enigma_ui.php
+++ b/plugins/enigma/lib/enigma_ui.php
@@ -730,6 +730,11 @@ class enigma_ui
         $menu->add(null, $chbox->show($this->rc->config->get('enigma_encrypt_all') ? 1 : 0,
             array('name' => '_enigma_encrypt', 'id' => 'enigmaencryptopt')));
 
+        $menu->add(null, html::label(array('for' => 'enigmaattachpubkeyopt'),
+            rcube::Q($this->enigma->gettext('attachpubkeymsg'))));
+        $menu->add(null, $chbox->show($this->rc->config->get('enigma_attach_pubkey') ? 1 : 0, 
+            array('name' => '_enigma_attachpubkey', 'id' => 'enigmaattachpubkeyopt')));
+
         $menu = html::div(array('id' => 'enigmamenu', 'class' => 'popupmenu'), $menu->show());
 
         // Options menu contents
@@ -929,12 +934,17 @@ class enigma_ui
     }
 
     /**
-     * Handle message_ready hook (encryption/signing)
+     * Handle message_ready hook (encryption/signing/attach public key)
      */
     function message_ready($p)
     {
         $savedraft = !empty($_POST['_draft']) && empty($_GET['_saveonly']);
 
+        if (!$savedraft && rcube_utils::get_input_value('_enigma_attachpubkey', rcube_utils::INPUT_POST)) {
+            $this->enigma->load_engine();
+            $this->enigma->engine->attach_public_key($p['message']);
+        }
+
         if (!$savedraft && rcube_utils::get_input_value('_enigma_sign', rcube_utils::INPUT_POST)) {
             $this->enigma->load_engine();
             $status = $this->enigma->engine->sign_message($p['message']);
@@ -971,7 +981,7 @@ class enigma_ui
         return $p;
     }
 
-    /**
+   /**
      * Handler for message_compose_body hook
      * Display error when the message cannot be encrypted
      * and provide a way to try again with a password.
diff --git a/plugins/enigma/localization/en_US.inc b/plugins/enigma/localization/en_US.inc
index 0e4d2b43d..5224ca556 100644
--- a/plugins/enigma/localization/en_US.inc
+++ b/plugins/enigma/localization/en_US.inc
@@ -53,6 +53,7 @@ $labels['supportsignatures'] = 'Enable message signatures verification';
 $labels['supportdecryption'] = 'Enable message decryption';
 $labels['signdefault'] = 'Sign all messages by default';
 $labels['encryptdefault'] = 'Encrypt all messages by default';
+$labels['attachpubkeydefault'] = 'Attach my public PGP key by default';
 $labels['passwordtime'] = 'Keep private key passwords for';
 $labels['nminutes'] = '$m minute(s)';
 $labels['wholesession'] = 'the whole session';
@@ -82,6 +83,7 @@ $labels['signmsg'] = 'Digitally sign this message';
 $labels['enterkeypasstitle'] = 'Enter key passphrase';
 $labels['enterkeypass'] = 'A passphrase is needed to unlock the secret key ($keyid) for user: $user.';
 $labels['arialabelkeyexportoptions'] = 'Keys export options';
+$labels['attachpubkeymsg'] = 'Attach my public key';
 
 $messages = array();
 $messages['sigvalid'] = 'Verified signature from $sender.';
diff --git a/plugins/managesieve/lib/Roundcube/rcube_sieve_engine.php b/plugins/managesieve/lib/Roundcube/rcube_sieve_engine.php
index 3fb168443..50f4c08d8 100644
--- a/plugins/managesieve/lib/Roundcube/rcube_sieve_engine.php
+++ b/plugins/managesieve/lib/Roundcube/rcube_sieve_engine.php
@@ -334,7 +334,7 @@ class rcube_sieve_engine
             else if ($action == 'act' && !$error) {
                 if (isset($this->script[$fid])) {
                     $rule     = $this->script[$fid];
-                    $disabled = $rule['disabled'] ? true : false;
+                    $disabled = !empty($rule['disabled']);
                     $rule['disabled'] = !$disabled;
                     $result = $this->sieve->script->update_rule($fid, $rule);
 
diff --git a/plugins/newmail_notifier/newmail_notifier.php b/plugins/newmail_notifier/newmail_notifier.php
index ca7953329..63a2cf884 100644
--- a/plugins/newmail_notifier/newmail_notifier.php
+++ b/plugins/newmail_notifier/newmail_notifier.php
@@ -159,7 +159,7 @@ class newmail_notifier extends rcube_plugin
         foreach (array('basic', 'desktop', 'sound') as $type) {
             $key = 'newmail_notifier_' . $type;
             if (!in_array($key, $dont_override)) {
-                $args['prefs'][$key] = rcube_utils::get_input_value('_'.$key, rcube_utils::INPUT_POST) ? true : false;
+                $args['prefs'][$key] = !empty(rcube_utils::get_input_value('_' . $key, rcube_utils::INPUT_POST));
             }
         }
 
diff --git a/program/lib/Roundcube/rcube_contacts.php b/program/lib/Roundcube/rcube_contacts.php
index 5ac575983..c9c01e46a 100644
--- a/program/lib/Roundcube/rcube_contacts.php
+++ b/program/lib/Roundcube/rcube_contacts.php
@@ -707,7 +707,7 @@ class rcube_contacts extends rcube_addressbook
             $this->result = null;  // clear current result (from get_record())
         }
 
-        return $updated ? true : false;
+        return !empty($updated);
     }
 
     /**
diff --git a/program/lib/Roundcube/rcube_imap.php b/program/lib/Roundcube/rcube_imap.php
index 5f532a50c..52ca22ccf 100644
--- a/program/lib/Roundcube/rcube_imap.php
+++ b/program/lib/Roundcube/rcube_imap.php
@@ -3304,6 +3304,12 @@ class rcube_imap extends rcube_storage
     public function get_special_folders($forced = false)
     {
         $result = parent::get_special_folders();
+        $rcube  = rcube::get_instance();
+
+        // Lock SPECIAL-USE after user preferences change (#4782)
+        if ($rcube->config->get('lock_special_folders')) {
+            return $result;
+        }
 
         if (isset($this->icache['special-use'])) {
             return array_merge($result, $this->icache['special-use']);
@@ -4278,7 +4284,7 @@ class rcube_imap extends rcube_storage
             $this->clear_cache('mailboxes', true);
         }
 
-        return $updated == count($folders) ? true : false;
+        return $updated == count($folders);
     }
 
     /**
diff --git a/program/lib/Roundcube/rcube_imap_generic.php b/program/lib/Roundcube/rcube_imap_generic.php
index 810dcce5f..764604d6a 100644
--- a/program/lib/Roundcube/rcube_imap_generic.php
+++ b/program/lib/Roundcube/rcube_imap_generic.php
@@ -1063,7 +1063,7 @@ class rcube_imap_generic
      */
     public function connected()
     {
-        return ($this->fp && $this->logged) ? true : false;
+        return $this->fp && $this->logged;
     }
 
     /**
diff --git a/program/lib/Roundcube/rcube_result_index.php b/program/lib/Roundcube/rcube_result_index.php
index 5ea390b2b..2f73c5e58 100644
--- a/program/lib/Roundcube/rcube_result_index.php
+++ b/program/lib/Roundcube/rcube_result_index.php
@@ -134,7 +134,7 @@ class rcube_result_index
      */
     public function is_error()
     {
-        return $this->raw_data === null ? true : false;
+        return $this->raw_data === null;
     }
 
     /**
@@ -144,7 +144,7 @@ class rcube_result_index
      */
     public function is_empty()
     {
-        return empty($this->raw_data) ? true : false;
+        return empty($this->raw_data);
     }
 
     /**
diff --git a/program/lib/Roundcube/rcube_result_thread.php b/program/lib/Roundcube/rcube_result_thread.php
index 5388eb109..c508a6625 100644
--- a/program/lib/Roundcube/rcube_result_thread.php
+++ b/program/lib/Roundcube/rcube_result_thread.php
@@ -89,7 +89,7 @@ class rcube_result_thread
      */
     public function is_error()
     {
-        return $this->raw_data === null ? true : false;
+        return $this->raw_data === null;
     }
 
     /**
@@ -99,7 +99,7 @@ class rcube_result_thread
      */
     public function is_empty()
     {
-        return empty($this->raw_data) ? true : false;
+        return empty($this->raw_data);
     }
 
     /**
diff --git a/program/steps/mail/show.inc b/program/steps/mail/show.inc
index 59ae13493..4183535f6 100644
--- a/program/steps/mail/show.inc
+++ b/program/steps/mail/show.inc
@@ -19,7 +19,7 @@
  +-----------------------------------------------------------------------+
 */
 
-$PRINT_MODE = $RCMAIL->action == 'print' ? TRUE : FALSE;
+$PRINT_MODE = $RCMAIL->action == 'print';
 
 // Read browser capabilities and store them in session
 if ($caps = rcube_utils::get_input_value('_caps', rcube_utils::INPUT_GET)) {
diff --git a/program/steps/settings/save_prefs.inc b/program/steps/settings/save_prefs.inc
index 4657454b9..a314aaf2b 100644
--- a/program/steps/settings/save_prefs.inc
+++ b/program/steps/settings/save_prefs.inc
@@ -5,7 +5,7 @@
  | program/steps/settings/save_prefs.inc                                 |
  |                                                                       |
  | This file is part of the Roundcube Webmail client                     |
- | Copyright (C) 2005-2013, The Roundcube Dev Team                       |
+ | Copyright (C) 2005-2016, The Roundcube Dev Team                       |
  |                                                                       |
  | Licensed under the GNU General Public License version 3 or            |
  | any later version with exceptions for skins & plugins.                |
@@ -16,6 +16,7 @@
  |                                                                       |
  +-----------------------------------------------------------------------+
  | Author: Thomas Bruederli <roundcube@gmail.com>                        |
+ | Author: Aleksander Machniak <alec@alec.pl>                            |
  +-----------------------------------------------------------------------+
 */
 
@@ -30,9 +31,9 @@ case 'general':
         'timezone'     => isset($_POST['_timezone']) ? rcube_utils::get_input_value('_timezone', rcube_utils::INPUT_POST) : $CONFIG['timezone'],
         'date_format'  => isset($_POST['_date_format']) ? rcube_utils::get_input_value('_date_format', rcube_utils::INPUT_POST) : $CONFIG['date_format'],
         'time_format'  => isset($_POST['_time_format']) ? rcube_utils::get_input_value('_time_format', rcube_utils::INPUT_POST) : ($CONFIG['time_format'] ? $CONFIG['time_format'] : 'H:i'),
-        'prettydate'   => isset($_POST['_pretty_date']) ? true : false,
+        'prettydate'   => isset($_POST['_pretty_date']),
         'refresh_interval' => isset($_POST['_refresh_interval']) ? intval($_POST['_refresh_interval'])*60 : $CONFIG['refresh_interval'],
-        'standard_windows' => isset($_POST['_standard_windows']) ? true : false,
+        'standard_windows' => isset($_POST['_standard_windows']),
         'skin'         => isset($_POST['_skin']) ? rcube_utils::get_input_value('_skin', rcube_utils::INPUT_POST) : $CONFIG['skin'],
     );
 
@@ -46,11 +47,11 @@ case 'general':
 
 case 'mailbox':
     $a_user_prefs = array(
-        'preview_pane'         => isset($_POST['_preview_pane']) ? true : false,
+        'preview_pane'         => isset($_POST['_preview_pane']),
         'preview_pane_mark_read' => isset($_POST['_preview_pane_mark_read']) ? intval($_POST['_preview_pane_mark_read']) : $CONFIG['preview_pane_mark_read'],
         'autoexpand_threads'   => isset($_POST['_autoexpand_threads']) ? intval($_POST['_autoexpand_threads']) : 0,
         'mdn_requests'         => isset($_POST['_mdn_requests']) ? intval($_POST['_mdn_requests']) : 0,
-        'check_all_folders'    => isset($_POST['_check_all_folders']) ? true : false,
+        'check_all_folders'    => isset($_POST['_check_all_folders']),
         'mail_pagesize'        => is_numeric($_POST['_mail_pagesize']) ? max(2, intval($_POST['_mail_pagesize'])) : $CONFIG['mail_pagesize'],
     );
 
@@ -59,11 +60,11 @@ case 'mailbox':
 case 'mailview':
     $a_user_prefs = array(
         'message_extwin'  => intval($_POST['_message_extwin']),
-        'message_show_email' => isset($_POST['_message_show_email']) ? true : false,
-        'prefer_html'     => isset($_POST['_prefer_html']) ? true : false,
-        'inline_images'   => isset($_POST['_inline_images']) ? true : false,
+        'message_show_email' => isset($_POST['_message_show_email']),
+        'prefer_html'     => isset($_POST['_prefer_html']),
+        'inline_images'   => isset($_POST['_inline_images']),
         'show_images'     => isset($_POST['_show_images']) ? intval($_POST['_show_images']) : 0,
-        'display_next'    => isset($_POST['_display_next']) ? true : false,
+        'display_next'    => isset($_POST['_display_next']),
         'default_charset' => rcube_utils::get_input_value('_default_charset', rcube_utils::INPUT_POST),
     );
 
@@ -75,19 +76,19 @@ case 'compose':
         'htmleditor'         => intval($_POST['_htmleditor']),
         'draft_autosave'     => isset($_POST['_draft_autosave']) ? intval($_POST['_draft_autosave']) : 0,
         'mime_param_folding' => isset($_POST['_mime_param_folding']) ? intval($_POST['_mime_param_folding']) : 0,
-        'force_7bit'         => isset($_POST['_force_7bit']) ? true : false,
-        'mdn_default'        => isset($_POST['_mdn_default']) ? true : false,
-        'dsn_default'        => isset($_POST['_dsn_default']) ? true : false,
-        'reply_same_folder'  => isset($_POST['_reply_same_folder']) ? true : false,
-        'spellcheck_before_send' => isset($_POST['_spellcheck_before_send']) ? true : false,
-        'spellcheck_ignore_syms' => isset($_POST['_spellcheck_ignore_syms']) ? true : false,
-        'spellcheck_ignore_nums' => isset($_POST['_spellcheck_ignore_nums']) ? true : false,
-        'spellcheck_ignore_caps' => isset($_POST['_spellcheck_ignore_caps']) ? true : false,
+        'force_7bit'         => isset($_POST['_force_7bit']),
+        'mdn_default'        => isset($_POST['_mdn_default']),
+        'dsn_default'        => isset($_POST['_dsn_default']),
+        'reply_same_folder'  => isset($_POST['_reply_same_folder']),
+        'spellcheck_before_send' => isset($_POST['_spellcheck_before_send']),
+        'spellcheck_ignore_syms' => isset($_POST['_spellcheck_ignore_syms']),
+        'spellcheck_ignore_nums' => isset($_POST['_spellcheck_ignore_nums']),
+        'spellcheck_ignore_caps' => isset($_POST['_spellcheck_ignore_caps']),
         'show_sig'           => isset($_POST['_show_sig']) ? intval($_POST['_show_sig']) : 1,
         'reply_mode'         => isset($_POST['_reply_mode']) ? intval($_POST['_reply_mode']) : 0,
-        'sig_below'          => isset($_POST['_sig_below']) ? true : false,
+        'sig_below'          => isset($_POST['_sig_below']),
         'strip_existing_sig' => isset($_POST['_strip_existing_sig']),
-        'sig_separator'      => isset($_POST['_sig_separator']) ? true : false,
+        'sig_separator'      => isset($_POST['_sig_separator']),
         'default_font'       => rcube_utils::get_input_value('_default_font', rcube_utils::INPUT_POST),
         'default_font_size'  => rcube_utils::get_input_value('_default_font_size', rcube_utils::INPUT_POST),
         'reply_all_mode'     => intval($_POST['_reply_all_mode']),
@@ -100,7 +101,7 @@ case 'compose':
 case 'addressbook':
     $a_user_prefs = array(
         'default_addressbook'  => rcube_utils::get_input_value('_default_addressbook', rcube_utils::INPUT_POST, true),
-        'autocomplete_single'  => isset($_POST['_autocomplete_single']) ? true : false,
+        'autocomplete_single'  => isset($_POST['_autocomplete_single']),
         'addressbook_sort_col' => rcube_utils::get_input_value('_addressbook_sort_col', rcube_utils::INPUT_POST),
         'addressbook_name_listing' => intval(rcube_utils::get_input_value('_addressbook_name_listing', rcube_utils::INPUT_POST)),
         'addressbook_pagesize' => is_numeric($_POST['_addressbook_pagesize']) ? max(2, intval($_POST['_addressbook_pagesize'])) : $CONFIG['addressbook_pagesize'],
@@ -110,20 +111,22 @@ case 'addressbook':
 
 case 'server':
     $a_user_prefs = array(
-        'read_when_deleted' => isset($_POST['_read_when_deleted']) ? true : false,
-        'skip_deleted'      => isset($_POST['_skip_deleted']) ? true : false,
-        'flag_for_deletion' => isset($_POST['_flag_for_deletion']) ? true : false,
-        'delete_always'     => isset($_POST['_delete_always']) ? true : false,
-        'delete_junk'       => isset($_POST['_delete_junk']) ? true : false,
-        'logout_purge'      => isset($_POST['_logout_purge']) ? true : false,
-        'logout_expunge'    => isset($_POST['_logout_expunge']) ? true : false,
+        'read_when_deleted' => isset($_POST['_read_when_deleted']),
+        'skip_deleted'      => isset($_POST['_skip_deleted']),
+        'flag_for_deletion' => isset($_POST['_flag_for_deletion']),
+        'delete_always'     => isset($_POST['_delete_always']),
+        'delete_junk'       => isset($_POST['_delete_junk']),
+        'logout_purge'      => isset($_POST['_logout_purge']),
+        'logout_expunge'    => isset($_POST['_logout_expunge']),
     );
 
     break;
 
 case 'folders':
     $a_user_prefs = array(
-        'show_real_foldernames' => isset($_POST['_show_real_foldernames']) ? true : false,
+        'show_real_foldernames' => isset($_POST['_show_real_foldernames']),
+        // stop using SPECIAL-USE (#4782)
+        'lock_special_folders'  => !in_array('lock_special_folders', (array) $CONFIG['dont_override']),
     );
 
     foreach (rcube_storage::$folder_types as $type) {