diff --git a/plugins/password/drivers/dovecot_passwdfile.php b/plugins/password/drivers/dovecot_passwdfile.php
new file mode 100644
index 00000000000..93db8d11aba
--- /dev/null
+++ b/plugins/password/drivers/dovecot_passwdfile.php
@@ -0,0 +1,196 @@
+<?php
+
+/**
+ * Dovecot passwdfile Password Driver
+ *
+ * Driver that adds functionality to change the passwords in dovecot 2 passwd-file files.
+ * The code is derrived from the Plugin examples by The Roundcube Dev Team
+ *
+ * Intentionally written for hostnet.de Managed-Root Server Systems, it determines
+ * the hostBSD System to preset any needed settings. hostNET Managed-Root Customers only need to set
+ *
+ * $config['password_driver'] = 'dovecot_passwdfile'
+ *
+ * in roundcubes plugins/password/config.inc.php to have all set.
+ * (But don't forget to enable the 'password' plugin at all...)
+ *
+ * On vanilla dovecot 2 environments, use the correct values for these config settings, too:
+ *
+ * $config['password_dovecot_passwdfile_path']: The path of your dovecot passwd-file '/path/to/filename' as set in dovecot/conf.d/auth-passwdfile.conf.ext
+ * $config['password_dovecotpw']: Full path and 'pw' command of doveadm binary - like '/usr/local/bin/doveadm pw'
+ * $config['password_dovecotpw_method']: Dovecot hashing algo (http://wiki2.dovecot.org/Authentication/PasswordSchemes)
+ * $config['password_dovecotpw_with_method']: True if you want the hashing algo as prefix in your passwd-file
+ *
+ * @version 1.0; Jimmy Koerting
+ *
+ * Copyright (C) 2017, hostNET Medien GmbH, www.hostnet.de
+ *
+ *
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see http://www.gnu.org/licenses/.
+ */
+
+
+class rcube_dovecot_passwdfile_password
+{
+    public function save($currpass, $newpass)
+    {
+        $rcmail           = rcmail::get_instance();
+        $username         = escapeshellcmd($_SESSION['username']);
+        $password         = $newpass;
+        $mailuserfile     = $rcmail->config->get('password_dovecot_passwdfile_path', '/etc/mail/mailuser');
+        $dovecotpw        = $rcmail->config->get('password_dovecotpw', '/usr/local/bin/doveadm pw');
+        $method           = $rcmail->config->get('password_dovecotpw_method', 'SHA512-CRYPT');
+        $with_method      = $rcmail->config->get('password_dovecotpw_with_method', false);
+
+        // BEGIN hostNET.de specific code - ignored elsewhere
+        $uname_call = "/usr/bin/uname -v";
+        exec($uname_call, $systemname, $return_value);
+        $systemname = implode($systemname);
+        if (strncmp ($systemname, 'hostBSD', 7) === 0) {
+                $mailuserfile     = '/etc/mail/mailuser';
+                $dovecotpw = '/usr/iports/bin/doveadm pw';
+                $method  = 'SHA512-CRYPT';
+                $with_method = false;
+        }
+        // END hostNET.de specific code
+
+
+        // simplified version from password::hash_password
+        $tmp_dir = $rcmail->config->get('temp_dir');
+        $tmpfile = tempnam($tmp_dir, 'roundcube-');
+
+        $pipe = popen("$dovecotpw -s '$method' > '$tmpfile'", "w");
+        if (!$pipe) {
+                unlink($tmpfile);
+                rcube::raise_error(array(
+                    'code' => 600,
+                    'type' => 'php',
+                    'file' => __FILE__, 'line' => __LINE__,
+                    'message' => "Password plugin: Can't create tempfile $tmpfile"
+                    ), true, false);
+                return PASSWORD_CRYPT_ERROR;
+        }
+        else {
+                fwrite($pipe, $password . "\n", 1+strlen($password)); usleep(1000);
+                fwrite($pipe, $password . "\n", 1+strlen($password));
+                pclose($pipe);
+
+                $newhash = trim(file_get_contents($tmpfile), "\n");
+                unlink($tmpfile);
+
+                if (!preg_match('/^\{' . $method . '\}/', $newhash)) {
+                    rcube::raise_error(array(
+                        'code' => 600,
+                        'type' => 'php',
+                        'file' => __FILE__, 'line' => __LINE__,
+                        'message' => "Password plugin: Password hashing failed -> $newhash"
+                        ), true, false);
+                    return PASSWORD_CRYPT_ERROR;
+                }
+
+                if(!$with_method) {
+                        $newhash = trim(str_replace('{' . $method . '}', '', $newhash));
+                }
+        }
+
+        $newhash = escapeshellcmd($newhash);
+
+        // read the entire mailuser file
+        $mailusercontent = file_get_contents($mailuserfile);
+
+        if (empty($mailusercontent)) {
+            // Error if the mailuserfile is empty/not accessible.
+            rcube::raise_error(array(
+                'code' => 600,
+                'type' => 'php',
+                'file' => __FILE__, 'line' => __LINE__,
+                'message' => "Password plugin: Unable to get old password file - $mailuserfile."
+                ), true, false);
+            return PASSWORD_CONNECT_ERROR;
+        }
+
+        // build the search/replace pattern.
+        $pattern = "/$username:[^:]+:/i";
+        $replace = "$username:$newhash:";
+
+        // replace
+        $mailusercontent = preg_replace($pattern, $replace, $mailusercontent);
+        
+        if (preg_last_error()){
+            $error = $this->preg_error_message(preg_last_error());
+            rcube::raise_error(array(
+                'code' => 600,
+                'type' => 'php',
+                'file' => __FILE__, 'line' => __LINE__,
+                'message' => "Password plugin: Unable to replace the old password: $error."
+                ), true, false);
+            return PASSWORD_ERROR;
+        }
+
+        // write back the entire file
+        if (file_put_contents($mailuserfile, $mailusercontent)) {
+            return PASSWORD_SUCCESS;
+        }
+        else {
+            rcube::raise_error(array(
+                'code' => 600,
+                'type' => 'php',
+                'file' => __FILE__, 'line' => __LINE__,
+                'message' => "Password plugin: Unable to save new password."
+                ), true, false);
+        }
+
+        return PASSWORD_ERROR;
+    }
+    
+
+    /**
+     * Fire TEXT errors
+     * Derrived from
+     * @author Ivan Tcholakov, 2016
+     * @license MIT
+     */
+    function preg_error_message($code = null)
+    {
+        $code = (int) $code;
+        switch ($code) {
+            case PREG_NO_ERROR:
+                $result = 'No error, probably invalid regular expression?';
+                break;
+            case PREG_INTERNAL_ERROR:
+                $result = 'PCRE: Internal error.';
+                break;
+            case PREG_BACKTRACK_LIMIT_ERROR:
+                $result = 'PCRE: Backtrack limit has been exhausted.';
+                break;
+            case PREG_RECURSION_LIMIT_ERROR:
+                $result = 'PCRE: Recursion limit has been exhausted.';
+                break;
+            case PREG_BAD_UTF8_ERROR:
+                $result = 'PCRE: Malformed UTF-8 data.';
+                break;
+            default:
+                if (is_php('5.3') && $code == PREG_BAD_UTF8_OFFSET_ERROR) {
+                    $result = 'PCRE: Did not end at a valid UTF-8 codepoint.';
+                } elseif (is_php('7') && $code == PREG_JIT_STACKLIMIT_ERROR) {
+                    $result = 'PCRE: Failed because of limited JIT stack space.';
+                } else {
+                    $result = 'PCRE: Error ' . $code . '.';
+                }
+                break;
+        }
+        return $result;
+    }
+}