You need to create small module for this.
Using di.xml can rewrite the controller Post.php
First ,Create module registration file registration.php
at app\code\VendorName\ModuleName. Code is below:
<?php
\Magento\Framework\Component\ComponentRegistrar::register(
\Magento\Framework\Component\ComponentRegistrar::MODULE,
'VendorName_ModuleName',
__DIR__
);
Then create module main config module.xml
file at app\code\VendorName\ModuleName\etc. Code is below:
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
<module name="VendorName_ModuleName" setup_version="2.0.0">
<sequence>
<module name="Magento_Contact"/>
</sequence>
</module>
</config>
3rd, create di.xml
where you define configuration that which class will rewrite and which class rewriting and di.xml located at
app\code\VendorName\ModuleName\etc and code is below:
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
<preference for="Magento\Contact\Controller\Index\Post" type="VendorName\ModuleName\Controller\Index\Post" />
</config>
4th, write the rewrite class which located at Post.php
app\code\VendorName\ModuleName\Controller\Index.
<?php
namespace VendorName\ModuleName\Controller\Index;
class Post extends \Magento\Contact\Controller\Index\Post
{
/**
* Post user question
*
* @return void
* @throws \Exception
*/
public function execute()
{
$post = $this->getRequest()->getPostValue();
if (!$post) {
$this->_redirect('*/*/');
return;
}
$this->inlineTranslation->suspend();
try {
$postObject = new \Magento\Framework\DataObject();
$postObject->setData($post);
$error = false;
if (!\Zend_Validate::is(trim($post['name']), 'NotEmpty')) {
$error = true;
}
if (!\Zend_Validate::is(trim($post['comment']), 'NotEmpty')) {
$error = true;
}
if (!\Zend_Validate::is(trim($post['email']), 'EmailAddress')) {
$error = true;
}
if (\Zend_Validate::is(trim($post['hideit']), 'NotEmpty')) {
$error = true;
}
if ($error) {
throw new \Exception();
}
$storeScope = \Magento\Store\Model\ScopeInterface::SCOPE_STORE;
$transport = $this->_transportBuilder
->setTemplateIdentifier($this->scopeConfig->getValue(self::XML_PATH_EMAIL_TEMPLATE, $storeScope))
->setTemplateOptions(
[
'area' => \Magento\Backend\App\Area\FrontNameResolver::AREA_CODE,
'store' => \Magento\Store\Model\Store::DEFAULT_STORE_ID,
]
)
->setTemplateVars(['data' => $postObject])
->setFrom($this->scopeConfig->getValue(self::XML_PATH_EMAIL_SENDER, $storeScope))
->addTo($this->scopeConfig->getValue(self::XML_PATH_EMAIL_RECIPIENT, $storeScope))
->setReplyTo($post['email'])
->getTransport();
$transport->sendMessage();
$this->inlineTranslation->resume();
$this->messageManager->addSuccess(
__('Thanks for contacting us with your comments and questions. We\'ll respond to you very soon.')
);
$this->_redirect('YOUR_CMS_PAGE_Identifier'); // change here
return;
} catch (\Exception $e) {
$this->inlineTranslation->resume();
$this->messageManager->addError(
__('We can\'t process your request right now. Sorry, that\'s all we know.')
);
$this->_redirect('YOUR_CMS_PAGE_Identifier'); // change here
return;
}
}
}
Then clear cache.
NOte:This module is tested