some big beautiful update

application/Espo/Core/Mail/Account/GroupAccount/Service.php

@@ -30,16 +30,19 @@
 namespace Espo\Core\Mail\Account\GroupAccount;
 
 use Espo\Core\Exceptions\ErrorSilent;
+use Espo\Core\Exceptions\Forbidden;
 use Espo\Core\Mail\Account\Account as Account;
 use Espo\Core\Exceptions\Error;
 use Espo\Core\Mail\Account\Fetcher;
 use Espo\Core\Mail\Account\Storage\Params;
 use Espo\Core\Mail\Account\StorageFactory;
+use Espo\Core\Mail\Account\Util\AddressUtil;
 use Espo\Core\Mail\Account\Util\NotificationHelper;
 use Espo\Core\Mail\Exceptions\ImapError;
 use Espo\Core\Mail\Exceptions\NoImap;
 use Espo\Core\Mail\Sender\Message;
 use Espo\Core\Utils\Log;
+use Espo\Core\Utils\Security\HostCheck;
 use Exception;
 
 class Service
@@ -49,7 +52,9 @@ class Service
         private AccountFactory $accountFactory,
         private StorageFactory $storageFactory,
         private Log $log,
-        private NotificationHelper $notificationHelper
+        private NotificationHelper $notificationHelper,
+        private HostCheck $hostCheck,
+        private AddressUtil $addressUtil,
     ) {}
 
     /**
@@ -77,9 +82,18 @@ class Service
      * @return string[]
      * @throws Error
      * @throws ImapError
+     * @throws Forbidden
      */
     public function getFolderList(Params $params): array
     {
+        if (
+            $params->getHost() &&
+            !$this->addressUtil->isAllowedAddress($params) &&
+            !$this->hostCheck->isNotInternalHost($params->getHost())
+        ) {
+            throw new Forbidden("Not allowed internal host.");
+        }
+
         if ($params->getId()) {
             $account = $this->accountFactory->create($params->getId());
 
@@ -95,6 +109,7 @@ class Service
 
     /**
      * @throws Error
+     * @throws Forbidden
      */
     public function testConnection(Params $params): void
     {
@@ -106,6 +121,14 @@ class Service
                 ->withImapHandlerClassName($account->getImapHandlerClassName());
         }
 
+        if (
+            $params->getHost() &&
+            !$this->addressUtil->isAllowedAddress($params) &&
+            !$this->hostCheck->isNotInternalHost($params->getHost())
+        ) {
+            throw new Forbidden("Not allowed internal host.");
+        }
+
         try {
             $storage = $this->storageFactory->createWithParams($params);
             $storage->getFolderNames();

application/Espo/Core/Mail/Account/PersonalAccount/Service.php

@@ -30,9 +30,11 @@
 namespace Espo\Core\Mail\Account\PersonalAccount;
 
 use Espo\Core\Exceptions\ErrorSilent;
+use Espo\Core\Mail\Account\Util\AddressUtil;
 use Espo\Core\Mail\Account\Util\NotificationHelper;
 use Espo\Core\Mail\Exceptions\ImapError;
 use Espo\Core\Mail\Exceptions\NoImap;
+use Espo\Core\Utils\Config;
 use Espo\Core\Utils\Log;
 use Espo\Core\Mail\Account\Account as Account;
 use Espo\Core\Exceptions\Forbidden;
@@ -40,6 +42,7 @@ use Espo\Core\Exceptions\Error;
 use Espo\Core\Mail\Account\Fetcher;
 use Espo\Core\Mail\Account\Storage\Params;
 use Espo\Core\Mail\Account\StorageFactory;
+use Espo\Core\Utils\Security\HostCheck;
 use Espo\Entities\User;
 use Espo\Core\Mail\Sender\Message;
 
@@ -53,7 +56,9 @@ class Service
         private StorageFactory $storageFactory,
         private User $user,
         private Log $log,
-        private NotificationHelper $notificationHelper
+        private NotificationHelper $notificationHelper,
+        private HostCheck $hostCheck,
+        private AddressUtil $addressUtil,
     ) {}
 
     /**
@@ -95,6 +100,14 @@ class Service
             throw new Forbidden();
         }
 
+        if (
+            $params->getHost() &&
+            !$this->addressUtil->isAllowedAddress($params) &&
+            !$this->hostCheck->isNotInternalHost($params->getHost())
+        ) {
+            throw new Forbidden("Not allowed internal host.");
+        }
+
         if ($params->getId()) {
             $account = $this->accountFactory->create($params->getId());
 
@@ -128,6 +141,14 @@ class Service
             throw new Forbidden();
         }
 
+        if (
+            $params->getHost() &&
+            !$this->addressUtil->isAllowedAddress($params) &&
+            !$this->hostCheck->isNotInternalHost($params->getHost())
+        ) {
+            throw new Forbidden("Not allowed host.");
+        }
+
         if ($params->getId()) {
             $account = $this->accountFactory->create($params->getId());
 

application/Espo/Core/Mail/Account/Util/AddressUtil.php

@@ -0,0 +1,69 @@
+<?php
+/************************************************************************
+ * This file is part of EspoCRM.
+ *
+ * EspoCRM – Open Source CRM application.
+ * Copyright (C) 2014-2026 EspoCRM, Inc.
+ * Website: https://www.espocrm.com
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
+ * The interactive user interfaces in modified source and object code versions
+ * of this program must display Appropriate Legal Notices, as required under
+ * Section 5 of the GNU Affero General Public License version 3.
+ *
+ * In accordance with Section 7(b) of the GNU Affero General Public License version 3,
+ * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
+ ************************************************************************/
+
+namespace Espo\Core\Mail\Account\Util;
+
+use Espo\Core\Mail\Account\Storage\Params;
+use Espo\Core\Mail\SmtpParams;
+use Espo\Core\Utils\Config;
+
+/**
+ * @internal
+ */
+class AddressUtil
+{
+    public function __construct(
+        private Config $config,
+    ) {}
+
+    /**
+     * @internal
+     */
+    public function isAllowedAddress(Params|SmtpParams $params): bool
+    {
+        $host = $params instanceof Params ? $params->getHost() : $params->getServer();
+        $port = $params->getPort();
+
+        if ($port === null || !$host) {
+            return false;
+        }
+
+        $address = $host . ':' . $port;
+
+        return in_array($address, $this->getAllowedAddressList());
+    }
+
+    /**
+     * @return string[]
+     */
+    private function getAllowedAddressList(): array
+    {
+        return $this->config->get('emailServerAllowedAddressList') ?? [];
+    }
+}

application/Espo/Core/Mail/Importer/DefaultImporter.php

@@ -420,8 +420,8 @@ class DefaultImporter implements Importer
             $subject = '(No Subject)';
         }
 
-        if (strlen($subject) > self::SUBJECT_MAX_LENGTH) {
-            $subject = substr($subject, 0, self::SUBJECT_MAX_LENGTH);
+        if (mb_strlen($subject) > self::SUBJECT_MAX_LENGTH) {
+            $subject = mb_substr($subject, 0, self::SUBJECT_MAX_LENGTH);
         }
 
         return $subject;