diff --git a/program/include/rcmail.php b/program/include/rcmail.php
index de332923b07..bbbf31d75c2 100644
--- a/program/include/rcmail.php
+++ b/program/include/rcmail.php
@@ -645,14 +645,15 @@ public function session_init()
      * Perform login to the mail server and to the webmail service.
      * This will also create a new user entry if auto_create_user is configured.
      *
-     * @param string $username    Mail storage (IMAP) user name
-     * @param string $password    Mail storage (IMAP) password
-     * @param string $host        Mail storage (IMAP) host
-     * @param bool   $cookiecheck Enables cookie check
+     * @param string $username     Mail storage (IMAP) user name
+     * @param string $password     Mail storage (IMAP) password
+     * @param string $host         Mail storage (IMAP) host
+     * @param bool   $cookiecheck  Enables cookie check
+     * @param bool   $just_connect Breaks after successful connect
      *
      * @return bool True on success, False on failure
      */
-    public function login($username, $password, $host = null, $cookiecheck = false)
+    public function login($username, $password, $host = null, $cookiecheck = false, $just_connect = false)
     {
         $this->login_error = null;
 
@@ -771,6 +772,15 @@ public function login($username, $password, $host = null, $cookiecheck = false)
             return false;
         }
 
+        // Only set user if just wanting to connect
+        if ($just_connect) {
+            if (is_object($user)) {
+                $this->set_user($user);
+            }
+            return true;
+        }
+
+
         // user already registered -> update user's record
         if (is_object($user)) {
             // update last login timestamp
diff --git a/program/lib/Roundcube/rcube.php b/program/lib/Roundcube/rcube.php
index 69354e038f2..4d97fd5cda9 100644
--- a/program/lib/Roundcube/rcube.php
+++ b/program/lib/Roundcube/rcube.php
@@ -1862,6 +1862,41 @@ public function deliver_message($message, $from, $mailto, &$error,
 
         return $sent;
     }
+
+    /**
+     * Helper method to establish connection to an IMAP backend.
+     *
+     * @param rcube_storage $imap         IMAP storage handler
+     * @param string        $host         IMAP host
+     * @param string        $username     IMAP username
+     * @param string        $password     IMAP password
+     * @param int           $port         IMAP port to connect to
+     * @param string        $ssl          SSL schema or false if plain connection
+     * @param rcube_user    $user         Roundcube user (if it already exists)
+     * @param array         $imap_options Additional IMAP options
+     *
+     * @return bool Return true on successful login
+     */
+    public function imap_connect($imap, $host, $username, $password, $port, $ssl, $user = null, $imap_options = [])
+    {
+        // enable proxy authentication
+        if (!empty($imap_options)) {
+            $imap->set_options($imap_options);
+        }
+
+        // try to log in
+        if (!$imap->connect($host, $username, $password, $port, $ssl)) {
+            if ($user) {
+                $user->failed_login();
+            }
+
+            // Wait a second to slow down brute-force attacks (#1490549)
+            sleep(1);
+            return false;
+        }
+
+        return true;
+    }
 }
 
 /**