add mx server setting

app/Enums/ProductParams.php

@@ -27,5 +27,6 @@ class ProductParams
     const DOMAIN_BASE_SIZE          = 'domainBaseSize';
     const SWITCHER_ENABLED          = 'on';
     const SWITCHER_DISABLED         = 'off';
+    const MX_SERVER                 = 'mxserver';
 
 }

app/Enums/Zimbra.php

@@ -48,7 +48,6 @@ class Zimbra
 
 
     const DEFAULT_LOGIN_LINK = 'https://zimbra-server';
-    const DEFAULT_MX_SERVER = 'mxserver';
 
     const BASE_ACCOUNT_CONFIG = [
         'zimbraFeatureMailEnabled',

app/UI/Admin/ProductConfiguration/Pages/Sections/ZimbraSettings.php

@@ -113,7 +113,7 @@ class ZimbraSettings extends BoxSectionExtended implements AdminArea
         $field->setDescription('description');
         $right->addField($field);
 
-        $field = new Text('mx_server');
+        $field = new Text('mxserver');
         $field->setDescription('description');
         $right->addField($field);
 

app/UI/Admin/ProductConfiguration/Providers/ProductConfigurationDataProvider.php

@@ -41,7 +41,6 @@ class ProductConfigurationDataProvider extends BaseDataProvider implements Admin
             'dist_list_limit',
             'domainMaxSize',
             'domainBaseSize',
-            'mx_server',
             'cos',
             'ca_emailAccountPage',
             'ca_distributionListPage',
@@ -110,7 +109,7 @@ class ProductConfigurationDataProvider extends BaseDataProvider implements Admin
         $this->data['login_link']         = Zimbra::DEFAULT_LOGIN_LINK;
         $this->data['domainMaxSize']      = Size::UNLIMITED;
         $this->data['domainBaseSize']     = Size::UNLIMITED;
-        $this->data['mx_server']          = Zimbra::DEFAULT_MX_SERVER;
+        $this->data['mxserver']           = ProductParams::MX_SERVER;
 
         /* available class of services*/
         $this->availableValues['cos_name'] = [