diff --git a/plugins/calendar/drivers/kolab/kolab_calendar.php b/plugins/calendar/drivers/kolab/kolab_calendar.php
index a346037d..ccd542ae 100644
--- a/plugins/calendar/drivers/kolab/kolab_calendar.php
+++ b/plugins/calendar/drivers/kolab/kolab_calendar.php
@@ -145,7 +145,7 @@ class kolab_calendar
   public function get_foldername()
   {
     $parts = explode('/', $this->imap_folder);
-    return rcube_charset_convert(end($parts), 'UTF7-IMAP');
+    return rcube_charset::convert(end($parts), 'UTF7-IMAP');
   }
 
   /**
diff --git a/plugins/calendar/drivers/kolab/kolab_driver.php b/plugins/calendar/drivers/kolab/kolab_driver.php
index a55a8cc1..a70ddfef 100644
--- a/plugins/calendar/drivers/kolab/kolab_driver.php
+++ b/plugins/calendar/drivers/kolab/kolab_driver.php
@@ -78,7 +78,7 @@ class kolab_driver extends calendar_driver
       // convert to UTF8 and sort
       $names = array();
       foreach ($folders as $folder)
-        $names[$folder->name] = rcube_charset_convert($folder->name, 'UTF7-IMAP');
+        $names[$folder->name] = rcube_charset::convert($folder->name, 'UTF7-IMAP');
 
       asort($names, SORT_LOCALE_STRING);
 
@@ -160,8 +160,8 @@ class kolab_driver extends calendar_driver
     }
     
     // subscribe to new calendar by default
-    $this->rc->imap_connect();
-    $this->rc->imap->subscribe($folder);
+    $storage = $this->rc->get_storage();
+    $storage->subscribe($folder);
 
     // create ID
     $id = rcube_kolab::folder_id($folder);
@@ -226,11 +226,11 @@ class kolab_driver extends calendar_driver
   public function subscribe_calendar($prop)
   {
     if ($prop['id'] && ($cal = $this->calendars[$prop['id']])) {
-      $this->rc->imap_connect();
+      $storage = $this->rc->get_storage();
       if ($prop['active'])
-        return $this->rc->imap->subscribe($cal->get_realname());
+        return $storage->subscribe($cal->get_realname());
       else
-        return $this->rc->imap->unsubscribe($cal->get_realname());
+        return $storage->unsubscribe($cal->get_realname());
     }
     
     return false;
@@ -246,14 +246,14 @@ class kolab_driver extends calendar_driver
    */
   private function folder_update(&$prop)
   {
-    $folder    = rcube_charset_convert($prop['name'], RCMAIL_CHARSET, 'UTF7-IMAP');
+    $folder    = rcube_charset::convert($prop['name'], RCMAIL_CHARSET, 'UTF7-IMAP');
     $oldfolder = $prop['oldname']; // UTF7
     $parent    = $prop['parent']; // UTF7
-    $delimiter = $_SESSION['imap_delimiter'];
+    $storage   = $this->rc->get_storage();
+    $delimiter = $storage->get_hierarchy_delimiter();
 
     if (strlen($oldfolder)) {
-        $this->rc->imap_connect();
-        $options = $this->rc->imap->mailbox_info($oldfolder);
+        $options = $storage->folder_info($oldfolder);
     }
 
     if (!empty($options) && ($options['norename'] || $options['protected'])) {
@@ -285,14 +285,12 @@ class kolab_driver extends calendar_driver
     }
     else {
       // add namespace prefix (when needed)
-      $this->rc->imap_init();
-      $folder = $this->rc->imap->mod_mailbox($folder, 'in');
+      $folder = $storage->mod_folder($folder, 'in');
     }
 
     // Check access rights to the parent folder
     if (strlen($parent) && (!strlen($oldfolder) || $oldfolder != $folder)) {
-      $this->rc->imap_connect();
-      $parent_opts = $this->rc->imap->mailbox_info($parent);
+      $parent_opts = $storage->folder_info($parent);
       if ($parent_opts['namespace'] != 'personal'
         && (empty($parent_opts['rights']) || !preg_match('/[ck]/', implode($parent_opts)))
       ) {
@@ -320,8 +318,8 @@ class kolab_driver extends calendar_driver
     // TODO: also save 'showalarams' and other properties here
 
     if ($result && $prop['color']) {
-      if (!($meta_saved = $this->rc->imap->set_metadata($folder, array('/shared/vendor/kolab/color' => $prop['color']))))  // try in shared namespace
-        $meta_saved = $this->rc->imap->set_metadata($folder, array('/private/vendor/kolab/color' => $prop['color']));    // try in private namespace
+      if (!($meta_saved = $storage->set_metadata($folder, array('/shared/vendor/kolab/color' => $prop['color']))))  // try in shared namespace
+        $meta_saved = $storage->set_metadata($folder, array('/private/vendor/kolab/color' => $prop['color']));    // try in private namespace
       if ($meta_saved)
         unset($prop['color']);  // unsetting will prevent fallback to local user prefs
     }
@@ -1016,7 +1014,8 @@ class kolab_driver extends calendar_driver
 
     $hidden_fields[] = array('name' => 'oldname', 'value' => $folder);
 
-    $delim  = $_SESSION['imap_delimiter'];
+    $storage = $this->rc->get_storage();
+    $delim   = $storage->get_hierarchy_delimiter();
     $form   = array();
 
     if (strlen($folder)) {
@@ -1024,8 +1023,7 @@ class kolab_driver extends calendar_driver
       array_pop($path_imap);  // pop off name part
       $path_imap = implode($path_imap, $delim);
 
-      $this->rc->imap_connect();
-      $options = $this->rc->imap->mailbox_info($folder);
+      $options = $storage->folder_info($folder);
     }
     else {
       $path_imap = '';
@@ -1179,7 +1177,8 @@ class kolab_driver extends calendar_driver
 
     $hidden_fields[] = array('name' => 'oldname', 'value' => $folder);
 
-    $delim  = $_SESSION['imap_delimiter'];
+    $storage = $this->rc->get_storage();
+    $delim   = $storage->get_hierarchy_delimiter();
     $form   = array();
 
     if (strlen($folder)) {
@@ -1187,8 +1186,7 @@ class kolab_driver extends calendar_driver
       array_pop($path_imap);  // pop off name part
       $path_imap = implode($path_imap, $delim);
 
-      $this->rc->imap_connect();
-      $options = $this->rc->imap->mailbox_info($folder);
+      $options = $storage->folder_info($folder);
     
       // Allow plugins to modify the form content (e.g. with ACL form)
       $plugin = $this->rc->plugins->exec_hook('calendar_form_kolab',
diff --git a/plugins/kolab_addressbook/kolab_addressbook.php b/plugins/kolab_addressbook/kolab_addressbook.php
index ec75162a..5a47657d 100644
--- a/plugins/kolab_addressbook/kolab_addressbook.php
+++ b/plugins/kolab_addressbook/kolab_addressbook.php
@@ -131,7 +131,7 @@ class kolab_addressbook extends rcube_plugin
                 'editable' => $abook->editable,
                 'groups'   => $abook->groups,
                 'undelete' => $abook->undelete && $undelete,
-                'realname' => rcube_charset_convert($abook->get_realname(), 'UTF7-IMAP'), // IMAP folder name
+                'realname' => rcube_charset::convert($abook->get_realname(), 'UTF7-IMAP'), // IMAP folder name
                 'class_name' => $abook->get_namespace(),
                 'kolab'    => true,
             );
@@ -258,7 +258,7 @@ class kolab_addressbook extends rcube_plugin
             // convert to UTF8 and sort
             $names = array();
             foreach ($this->folders as $c_folder)
-                $names[$c_folder->name] = rcube_charset_convert($c_folder->name, 'UTF7-IMAP');
+                $names[$c_folder->name] = rcube_charset::convert($c_folder->name, 'UTF7-IMAP');
 
             asort($names, SORT_LOCALE_STRING);
 
@@ -420,14 +420,14 @@ class kolab_addressbook extends rcube_plugin
      */
     public function book_save()
     {
+        $storage   = $this->rc->get_storage();
         $folder    = trim(get_input_value('_name', RCUBE_INPUT_POST, true, 'UTF7-IMAP'));
         $oldfolder = trim(get_input_value('_oldname', RCUBE_INPUT_POST, true)); // UTF7-IMAP
         $path      = trim(get_input_value('_parent', RCUBE_INPUT_POST, true)); // UTF7-IMAP
-        $delimiter = $_SESSION['imap_delimiter'];
+        $delimiter = $storage->get_hierarchy_delimiter();
 
         if (strlen($oldfolder)) {
-            $this->rc->imap_connect();
-            $options = $this->rc->imap->mailbox_info($oldfolder);
+            $options = $storage->folder_info($oldfolder);
         }
 
         if (!empty($options) && ($options['norename'] || $options['protected'])) {
@@ -458,14 +458,12 @@ class kolab_addressbook extends rcube_plugin
             }
             else {
                 // add namespace prefix (when needed)
-                $this->rc->imap_init();
-                $folder = $this->rc->imap->mod_mailbox($folder, 'in');
+                $folder = $storage->mod_folder($folder, 'in');
             }
 
             // Check access rights to the parent folder
             if (strlen($path) && (!strlen($oldfolder) || $oldfolder != $folder)) {
-                $this->rc->imap_connect();
-                $parent_opts = $this->rc->imap->mailbox_info($path);
+                $parent_opts = $storage->folder_info($path);
                 if ($parent_opts['namespace'] != 'personal'
                     && (empty($parent_opts['rights']) || !preg_match('/[ck]/', implode($parent_opts)))
                 ) {
@@ -552,7 +550,7 @@ class kolab_addressbook extends rcube_plugin
                 'readonly' => false,
                 'editable' => true,
                 'groups'   => true,
-                'realname' => rcube_charset_convert($folder, 'UTF7-IMAP'), // IMAP folder name
+                'realname' => rcube_charset::convert($folder, 'UTF7-IMAP'), // IMAP folder name
                 'class_name' => $kolab_folder->get_namespace(),
                 'kolab'    => true,
             ), rcube_kolab::folder_id($oldfolder));
diff --git a/plugins/kolab_addressbook/lib/rcube_kolab_contacts.php b/plugins/kolab_addressbook/lib/rcube_kolab_contacts.php
index 9c40afb9..2ffc7407 100644
--- a/plugins/kolab_addressbook/lib/rcube_kolab_contacts.php
+++ b/plugins/kolab_addressbook/lib/rcube_kolab_contacts.php
@@ -131,8 +131,9 @@ class rcube_kolab_contacts extends rcube_addressbook
 
     public function __construct($imap_folder = null)
     {
-        if ($imap_folder)
+        if ($imap_folder) {
             $this->imap_folder = $imap_folder;
+        }
 
         // extend coltypes configuration 
         $format = rcube_kolab::get_format('contact');
@@ -653,8 +654,9 @@ class rcube_kolab_contacts extends rcube_addressbook
         }
 
         // store IMAP uids for undelete()
-        if (!$force)
+        if (!$force) {
             $_SESSION['kolab_delete_uids'] = $imap_uids;
+        }
 
         return $count;
     }
diff --git a/plugins/kolab_auth/kolab_auth.php b/plugins/kolab_auth/kolab_auth.php
index 3fa85248..07800cda 100644
--- a/plugins/kolab_auth/kolab_auth.php
+++ b/plugins/kolab_auth/kolab_auth.php
@@ -43,7 +43,7 @@ class kolab_auth extends rcube_plugin
 
         // Hooks related to "Login As" feature
         $this->add_hook('template_object_loginform', array($this, 'login_form'));
-        $this->add_hook('imap_connect', array($this, 'imap_connect'));
+        $this->add_hook('storage_connect', array($this, 'imap_connect'));
         $this->add_hook('managesieve_connect', array($this, 'imap_connect'));
         $this->add_hook('smtp_connect', array($this, 'smtp_connect'));
 
@@ -135,7 +135,7 @@ class kolab_auth extends rcube_plugin
                     } else {
                         $dont_override = $rcmail->config->get('dont_override');
                         if (in_array($setting_name, $dont_override)) {
-                            $_dont_override = Array();
+                            $_dont_override = array();
                             foreach ($dont_override as $_setting) {
                                 if ($_setting != $setting_name) {
                                     $_dont_override[] = $_setting;
diff --git a/plugins/kolab_core/rcube_kolab.php b/plugins/kolab_core/rcube_kolab.php
index 7f2702fc..6bd5f603 100644
--- a/plugins/kolab_core/rcube_kolab.php
+++ b/plugins/kolab_core/rcube_kolab.php
@@ -222,15 +222,9 @@ class rcube_kolab
       static $subscribed;  // local cache
 
       if (!$subscribed) {
-        $rcmail = rcmail::get_instance();
-        // try without connection first (list could be served from cache)
-        $subscribed = $rcmail->imap ? $rcmail->imap->list_mailboxes() : array();
-
-        // now really get the list from the IMAP server
-        if (empty($subscribed) || $subscribed == array('INBOX')) {
-          $rcmail->imap_connect();
-          $subscribed = $rcmail->imap->list_mailboxes();
-        }
+        $rcmail     = rcmail::get_instance();
+        $storage    = $rcmail->get_storage();
+        $subscribed = $storage->list_folders();
       }
 
       return in_array($folder, $subscribed);
@@ -390,10 +384,9 @@ class rcube_kolab
      */
     public static function object_name($folder, &$folder_ns=null)
     {
-        $rcmail = rcmail::get_instance();
-        $rcmail->imap_init();
-
-        $namespace = $rcmail->imap->get_namespace();
+        $rcmail    = rcmail::get_instance();
+        $storage   = $rcmail->get_storage();
+        $namespace = $storage->get_namespace();
         $found     = false;
 
         if (!empty($namespace['shared'])) {
@@ -444,9 +437,9 @@ class rcube_kolab
         }
 
         if (empty($delim))
-            $delim = $rcmail->imap->get_hierarchy_delimiter();
+            $delim = $storage->get_hierarchy_delimiter();
 
-        $folder = rcube_charset_convert($folder, 'UTF7-IMAP');
+        $folder = rcube_charset::convert($folder, 'UTF7-IMAP');
         $folder = str_replace($delim, ' » ', $folder);
 
         if ($prefix)
@@ -467,10 +460,9 @@ class rcube_kolab
      */
     public static function folder_namespace($folder)
     {
-        $rcmail = rcmail::get_instance();
-        $rcmail->imap_init();
-
-        $namespace = $rcmail->imap->get_namespace();
+        $rcmail    = rcmail::get_instance();
+        $storage   = $rcmail->get_storage();
+        $namespace = $storage->get_namespace();
 
         if (!empty($namespace)) {
             foreach ($namespace as $nsname => $nsvalue) {
@@ -498,10 +490,13 @@ class rcube_kolab
      */
     public static function folder_selector($type, $attrs, $current = '')
     {
+        $rcmail    = rcmail::get_instance();
+        $storage   = $rcmail->get_storage();
+
         // get all folders of specified type
         $folders = self::get_folders($type);
 
-        $delim = $_SESSION['imap_delimiter'];
+        $delim = $storage->get_hierarchy_delimiter();
         $names = array();
         $len   = strlen($current);
 
@@ -528,12 +523,12 @@ class rcube_kolab
                 }
             }
 
-            $names[$name] = rcube_charset_convert($name, 'UTF7-IMAP');
+            $names[$name] = rcube_charset::convert($name, 'UTF7-IMAP');
         }
 
         // Make sure parent folder is listed (might be skipped e.g. if it's namespace root)
         if ($p_len && !isset($names[$parent])) {
-            $names[$parent] = rcube_charset_convert($parent, 'UTF7-IMAP');
+            $names[$parent] = rcube_charset::convert($parent, 'UTF7-IMAP');
         }
 
         // Sort folders list
diff --git a/plugins/kolab_folders/kolab_folders.php b/plugins/kolab_folders/kolab_folders.php
index 446a091d..044f6364 100644
--- a/plugins/kolab_folders/kolab_folders.php
+++ b/plugins/kolab_folders/kolab_folders.php
@@ -41,7 +41,7 @@ class kolab_folders extends rcube_plugin
         $this->rc = rcmail::get_instance();
 
         // Folder listing hooks
-        $this->add_hook('mailboxes_list', array($this, 'mailboxes_list'));
+        $this->add_hook('storage_folders', array($this, 'mailboxes_list'));
 
         // Folder manager hooks
         $this->add_hook('folder_form', array($this, 'folder_form'));
@@ -72,7 +72,6 @@ class kolab_folders extends rcube_plugin
         $folderdata = $this->get_folder_type_list($args['root'].$args['name'], true);
 
         if (!is_array($folderdata)) {
-            $args['folders'] = false;
             return $args;
         }
 
@@ -91,9 +90,11 @@ class kolab_folders extends rcube_plugin
             return $args;
         }
 
+        $storage = $this->rc->get_storage();
+
         // Get folders list
         if ($args['mode'] == 'LIST') {
-            $args['folders'] = $this->rc->imap->conn->listMailboxes($args['root'], $args['name']);
+            $args['folders'] = $storage->conn->listMailboxes($args['root'], $args['name']);
         }
         else {
             $args['folders'] = $this->list_subscribed($args['root'], $args['name']);
@@ -200,16 +201,21 @@ class kolab_folders extends rcube_plugin
             $ctype = 'mail';
         }
 
+        $storage = $this->rc->get_storage();
+
         // Don't allow changing type of shared folder, according to ACL
         if (strlen($mbox)) {
-            $options = $this->rc->imap->mailbox_info($mbox);
+            $options = $storage->folder_info($mbox);
             if ($options['namespace'] != 'personal' && !in_array('a', $options['rights'])) {
-                if (in_array($ctype, $this->types))
+                if (in_array($ctype, $this->types)) {
                     $value = $this->gettext('foldertype'.$ctype);
-                else
+                }
+                else {
                     $value = $ctype;
-                if ($subtype)
+                }
+                if ($subtype) {
                     $value .= ' ('. ($subtype == 'default' ? $this->gettext('default') : $subtype) .')';
+                }
 
                 $args['form']['props']['fieldsets']['settings']['content']['foldertype'] = array(
                     'label' => $this->gettext('folderctype'),
@@ -298,13 +304,15 @@ class kolab_folders extends rcube_plugin
 
         $ctype .= $subtype ? '.'.$subtype : '';
 
+        $storage = $this->rc->get_storage();
+
         // Create folder
         if (!strlen($old_mbox)) {
             // By default don't subscribe to non-mail folders
             if ($subscribe)
                 $subscribe = (bool) preg_match('/^mail/', $ctype);
 
-            $result = $this->rc->imap->create_mailbox($mbox, $subscribe);
+            $result = $storage->create_folder($mbox, $subscribe);
             // Set folder type
             if ($result) {
                 $this->set_folder_type($mbox, $ctype);
@@ -313,7 +321,7 @@ class kolab_folders extends rcube_plugin
         // Rename folder
         else {
             if ($old_mbox != $mbox) {
-                $result = $this->rc->imap->rename_mailbox($old_mbox, $mbox);
+                $result = $storage->rename_folder($old_mbox, $mbox);
             }
             else {
                 $result = true;
@@ -348,9 +356,11 @@ class kolab_folders extends rcube_plugin
      */
     function metadata_support()
     {
-        return $this->rc->imap->get_capability('METADATA') ||
-            $this->rc->imap->get_capability('ANNOTATEMORE') ||
-            $this->rc->imap->get_capability('ANNOTATEMORE2');
+        $storage = $this->rc->get_storage();
+
+        return $storage->get_capability('METADATA') ||
+            $storage->get_capability('ANNOTATEMORE') ||
+            $storage->get_capability('ANNOTATEMORE2');
     }
 
     /**
@@ -362,7 +372,8 @@ class kolab_folders extends rcube_plugin
      */
     function get_folder_type($folder)
     {
-        $folderdata = $this->rc->imap->get_metadata($folder, array(kolab_folders::CTYPE_KEY));
+        $storage    = $this->rc->get_storage();
+        $folderdata = $storage->get_metadata($folder, array(kolab_folders::CTYPE_KEY));
 
         return explode('.', $folderdata[$folder][kolab_folders::CTYPE_KEY]);
     }
@@ -377,7 +388,9 @@ class kolab_folders extends rcube_plugin
      */
     function set_folder_type($folder, $type='mail')
     {
-        return $this->rc->imap->set_metadata($folder, array(kolab_folders::CTYPE_KEY => $type));
+        $storage = $this->rc->get_storage();
+
+        return $storage->set_metadata($folder, array(kolab_folders::CTYPE_KEY => $type));
     }
 
     /**
@@ -390,23 +403,23 @@ class kolab_folders extends rcube_plugin
      */
     private function list_subscribed($root='', $name='*')
     {
-        $imap = $this->rc->imap;
+        $storage = $this->rc->get_storage();
 
         // Code copied from rcube_imap::_list_mailboxes()
         // Server supports LIST-EXTENDED, we can use selection options
         // #1486225: Some dovecot versions returns wrong result using LIST-EXTENDED
         if (!$this->rc->config->get('imap_force_lsub') && $imap->get_capability('LIST-EXTENDED')) {
             // This will also set mailbox options, LSUB doesn't do that
-            $a_folders = $imap->conn->listMailboxes($root, $name,
+            $a_folders = $storage->conn->listMailboxes($root, $name,
                 NULL, array('SUBSCRIBED'));
 
             // remove non-existent folders
             if (is_array($a_folders) && $name = '*') {
                 foreach ($a_folders as $idx => $folder) {
-                    if ($imap->conn->data['LIST'] && ($opts = $imap->conn->data['LIST'][$folder])
+                    if ($storage->conn->data['LIST'] && ($opts = $storage->conn->data['LIST'][$folder])
                         && in_array('\\NonExistent', $opts)
                     ) {
-                        $imap->conn->unsubscribe($folder);
+                        $storage->conn->unsubscribe($folder);
                         unset($a_folders[$idx]);
                     }
                 }
@@ -414,17 +427,17 @@ class kolab_folders extends rcube_plugin
         }
         // retrieve list of folders from IMAP server using LSUB
         else {
-            $a_folders = $imap->conn->listSubscribed($root, $name);
+            $a_folders = $storage->conn->listSubscribed($root, $name);
 
             // unsubscribe non-existent folders, remove from the list
             if (is_array($a_folders) && $name == '*') {
                 foreach ($a_folders as $idx => $folder) {
-                    if ($imap->conn->data['LIST'] && ($opts = $imap->conn->data['LIST'][$folder])
+                    if ($storage->conn->data['LIST'] && ($opts = $storage->conn->data['LIST'][$folder])
                         && in_array('\\Noselect', $opts)
                     ) {
                         // Some servers returns \Noselect for existing folders
-                        if (!$imap->mailbox_exists($folder)) {
-                            $imap->conn->unsubscribe($folder);
+                        if (!$storage->folder_exists($folder)) {
+                            $storage->conn->unsubscribe($folder);
                             unset($a_folders[$idx]);
                         }
                     }
@@ -445,15 +458,17 @@ class kolab_folders extends rcube_plugin
      */
     function get_folder_type_list($mbox, $create_defaults = false)
     {
+        $storage = $this->rc->get_storage();
+
         // Use mailboxes. prefix so the cache will be cleared by core
         // together with other mailboxes-related cache data
         $cache_key = 'mailboxes.folder-type.'.$mbox;
 
         // get cached metadata
-        $metadata = $this->rc->imap->get_cache($cache_key);
+        $metadata = $storage->get_cache($cache_key);
 
         if (!is_array($metadata)) {
-            $metadata = $this->rc->imap->get_metadata($mbox, kolab_folders::CTYPE_KEY);
+            $metadata = $storage->get_metadata($mbox, kolab_folders::CTYPE_KEY);
             $need_update = true;
         }
 
@@ -473,7 +488,7 @@ class kolab_folders extends rcube_plugin
 
         // write mailboxlist to cache
         if ($need_update) {
-            $this->rc->imap->update_cache($cache_key, $metadata);
+            $storage->update_cache($cache_key, $metadata);
         }
 
         return $metadata;
@@ -488,6 +503,7 @@ class kolab_folders extends rcube_plugin
      */
     function get_default_folder($type)
     {
+        $storage    = $this->rc->get_storage();
         $folderdata = $this->get_folder_type_list('*');
 
         if (!is_array($folderdata)) {
@@ -495,7 +511,7 @@ class kolab_folders extends rcube_plugin
         }
 
         $type     .= '.default';
-        $namespace = $this->rc->imap->get_namespace();
+        $namespace = $storage->get_namespace();
 
         // get all folders of specified type
         $folderdata = array_intersect($folderdata, array($type)); 
@@ -552,7 +568,8 @@ class kolab_folders extends rcube_plugin
      */
     private function create_default_folders(&$folderdata, $cache_key = null)
     {
-        $namespace   = $this->rc->imap->get_namespace();
+        $storage     = $this->rc->get_storage();
+        $namespace   = $storage->get_namespace();
         $defaults    = array();
         $need_update = false;
 
@@ -573,7 +590,7 @@ class kolab_folders extends rcube_plugin
                 $opt_name = 'kolab_folders_' . $type . '_' . $subtype;
                 if ($folder = $this->rc->config->get($opt_name)) {
                     // convert configuration value to UTF7-IMAP charset
-                    $folder = rcube_charset_convert($folder, RCMAIL_CHARSET, 'UTF7-IMAP');
+                    $folder = rcube_charset::convert($folder, RCMAIL_CHARSET, 'UTF7-IMAP');
                     // and namespace prefix if needed
                     if ($prefix && strpos($folder, $prefix) === false && $folder != 'INBOX') {
                         $folder = $prefix . $folder;
@@ -621,8 +638,8 @@ class kolab_folders extends rcube_plugin
             list($type1, $type2) = explode('.', $type);
 
             // create folder
-            if ($type1 != 'mail' || !$this->rc->imap->mailbox_exists($foldername)) {
-                $this->rc->imap->create_mailbox($foldername, $type1 == 'mail');
+            if ($type1 != 'mail' || !$storage->folder_exists($foldername)) {
+                $storage->create_folder($foldername, $type1 == 'mail');
             }
 
             // set type
@@ -637,7 +654,8 @@ class kolab_folders extends rcube_plugin
 
         // update cache
         if ($need_update && $cache_key) {
-            $this->rc->imap->update_cache($cache_key, $folderdata);
+            $storage->update_cache($cache_key, $folderdata);
         }
     }
+
 }
diff --git a/plugins/kolab_zpush/kolab_zpush.php b/plugins/kolab_zpush/kolab_zpush.php
index 7624cd00..f19fe3ad 100644
--- a/plugins/kolab_zpush/kolab_zpush.php
+++ b/plugins/kolab_zpush/kolab_zpush.php
@@ -64,11 +64,12 @@ class kolab_zpush extends rcube_plugin
      */
     public function init_imap()
     {
-        $this->rc->imap_connect();
+        $storage = $this->rc->get_storage();
+
         $this->cache = $this->rc->get_cache('zpush', 'db', 900);
         $this->cache->expunge();
 
-        if ($meta = $this->rc->imap->get_metadata(self::ROOT_MAILBOX, self::ACTIVESYNC_KEY)) {
+        if ($meta = $storage->get_metadata(self::ROOT_MAILBOX, self::ACTIVESYNC_KEY)) {
             // clear cache if device config changed
             if (($oldmeta = $this->cache->read('devicemeta')) && $oldmeta != $meta)
                 $this->cache->remove();
@@ -85,13 +86,13 @@ class kolab_zpush extends rcube_plugin
      */
     public function json_command()
     {
-        $cmd = get_input_value('cmd', RCUBE_INPUT_GPC);
-        $imei = get_input_value('id', RCUBE_INPUT_GPC);
+        $storage = $this->rc->get_storage();
+        $cmd     = get_input_value('cmd', RCUBE_INPUT_GPC);
+        $imei    = get_input_value('id', RCUBE_INPUT_GPC);
 
         switch ($cmd) {
         case 'load':
             $result = array();
-            $this->init_imap();
             $devices = $this->list_devices();
             if ($device = $devices[$imei]) {
                 $result['id'] = $imei;
@@ -113,7 +114,6 @@ class kolab_zpush extends rcube_plugin
             break;
 
         case 'save':
-            $this->init_imap();
             $devices = $this->list_devices();
             $syncmode = intval(get_input_value('syncmode', RCUBE_INPUT_POST));
             $devicealias = get_input_value('devicealias', RCUBE_INPUT_POST, true);
@@ -132,13 +132,13 @@ class kolab_zpush extends rcube_plugin
                     $this->root_meta['DEVICE'][$imei]['LAXPIC'] = $laxpic;
                     $this->root_meta['FOLDER'][$imei]['S'] = intval($subsciptions[self::ROOT_MAILBOX]);
 
-                    $err = !$this->rc->imap->set_metadata(self::ROOT_MAILBOX,
+                    $err = !$storage->set_metadata(self::ROOT_MAILBOX,
                         array(self::ACTIVESYNC_KEY => $this->serialize_metadata($this->root_meta)));
 
                     // update cached meta data
                     if (!$err) {
                         $this->cache->remove('devicemeta');
-                        $this->cache->write('devicemeta', $this->rc->imap->get_metadata(self::ROOT_MAILBOX, self::ACTIVESYNC_KEY));
+                        $this->cache->write('devicemeta', $storage->get_metadata(self::ROOT_MAILBOX, self::ACTIVESYNC_KEY));
                     }
                 }
                 // iterate over folders list and update metadata if necessary
@@ -153,12 +153,12 @@ class kolab_zpush extends rcube_plugin
                         unset($meta['TYPE']);
                         
                         // read metadata first
-                        $folderdata = $this->rc->imap->get_metadata($folder, array(self::ACTIVESYNC_KEY));
+                        $folderdata = $storage->get_metadata($folder, array(self::ACTIVESYNC_KEY));
                         if ($asyncdata = $folderdata[$folder][self::ACTIVESYNC_KEY])
                             $metadata = $this->unserialize_metadata($asyncdata);
                         $metadata['FOLDER'] = $meta;
 
-                        $err |= !$this->rc->imap->set_metadata($folder, array(self::ACTIVESYNC_KEY => $this->serialize_metadata($metadata)));
+                        $err |= !$storage->set_metadata($folder, array(self::ACTIVESYNC_KEY => $this->serialize_metadata($metadata)));
                     }
                 }
                 
@@ -184,9 +184,9 @@ class kolab_zpush extends rcube_plugin
                 unset($this->root_meta['DEVICE'][$imei], $this->root_meta['FOLDER'][$imei]);
 
                 // update annotation and cached meta data
-                if ($success = $this->rc->imap->set_metadata(self::ROOT_MAILBOX, array(self::ACTIVESYNC_KEY => $this->serialize_metadata($this->root_meta)))) {
+                if ($success = $storage->set_metadata(self::ROOT_MAILBOX, array(self::ACTIVESYNC_KEY => $this->serialize_metadata($this->root_meta)))) {
                     $this->cache->remove('devicemeta');
-                    $this->cache->write('devicemeta', $this->rc->imap->get_metadata(self::ROOT_MAILBOX, self::ACTIVESYNC_KEY));
+                    $this->cache->write('devicemeta', $storage->get_metadata(self::ROOT_MAILBOX, self::ACTIVESYNC_KEY));
 
                     // remove device annotation in every folder
                     foreach ($this->folders_meta() as $folder => $meta) {
@@ -199,12 +199,12 @@ class kolab_zpush extends rcube_plugin
                             unset($meta[$imei], $meta['TYPE']);
 
                             // read metadata first and update FOLDER property
-                            $folderdata = $this->rc->imap->get_metadata($folder, array(self::ACTIVESYNC_KEY));
+                            $folderdata = $storage->get_metadata($folder, array(self::ACTIVESYNC_KEY));
                             if ($asyncdata = $folderdata[$folder][self::ACTIVESYNC_KEY])
                                 $metadata = $this->unserialize_metadata($asyncdata);
                             $metadata['FOLDER'] = $meta;
 
-                            if ($this->rc->imap->set_metadata($folder, array(self::ACTIVESYNC_KEY => $this->serialize_metadata($metadata)))) {
+                            if ($storage->set_metadata($folder, array(self::ACTIVESYNC_KEY => $this->serialize_metadata($metadata)))) {
                                 $this->folders_meta[$folder] = $metadata;
                                 $this->folders_meta[$folder]['TYPE'] = $type;
                             }
@@ -236,12 +236,12 @@ class kolab_zpush extends rcube_plugin
      */
     public function config_view()
     {
-        require_once($this->home . '/kolab_zpush_ui.php');
+        require_once $this->home . '/kolab_zpush_ui.php';
         
-        $this->init_imap();
+        $storage = $this->rc->get_storage();
         
         // checks if IMAP server supports any of METADATA, ANNOTATEMORE, ANNOTATEMORE2
-        if (!($this->rc->imap->get_capability('METADATA') || $this->rc->imap->get_capability('ANNOTATEMORE') || $this->rc->imap->get_capability('ANNOTATEMORE2'))) {
+        if (!($storage->get_capability('METADATA') || $storage->get_capability('ANNOTATEMORE') || $storage->get_capability('ANNOTATEMORE2'))) {
             $this->rc->output->show_message($this->gettext('notsupported'), 'error');
         }
         
@@ -286,9 +286,11 @@ class kolab_zpush extends rcube_plugin
             }
             // fetch folder data from server
             else {
-                $this->folders = $this->rc->imap->list_folders();
+                $storage       = $this->rc->get_storage();
+                $this->folders = $storage->list_folders();
+
                 foreach ($this->folders as $folder) {
-                    $folderdata = $this->rc->imap->get_metadata($folder, array(self::ACTIVESYNC_KEY, self::CTYPE_KEY));
+                    $folderdata = $storage->get_metadata($folder, array(self::ACTIVESYNC_KEY, self::CTYPE_KEY));
                     $foldertype = explode('.', $folderdata[$folder][self::CTYPE_KEY]);
 
                     if ($asyncdata = $folderdata[$folder][self::ACTIVESYNC_KEY]) {