Contact form 7 and Mailchimp Integration without plugin with action URL

functions.php

<?php 
/**
* This is a demo of mailchimp integration with contact form 7 with the help of Action URL.
* 
* You can get these action URL from the mailchimp list 
* follow this https://www.youtube.com/watch?v=sybmI8HgxFo 
* 
*/
// define the wpcf7_mail_sent callback 
function cf7_action_wpcf7_mail_sent( $contact_form ) { 
    
    $submission = WPCF7_Submission::get_instance();
    
    if ( $submission ) {
        $posted_data = $submission->get_posted_data();
    }
    
    $contact_form_id = $contact_form->id(); 
    if ( 123 == $contact_form_id ) { // check for contact form id
        
        if ( $submission ) {
            $posted_data = $submission->get_posted_data();
        }

        $target_data = array(
            'EMAIL' => $posted_data['your-email'],
            'FNAME' => $posted_data['your-name'],
            'LNAME' => $posted_data['your-last'],
        );
        // here I am getting selected mailchimp mailing list. Added in contact form 7 as a checkbox.
        $maillist = ( isset( $posted_data['checkbox-442'] ) && !empty( $posted_data['checkbox-442'] ))? $posted_data['checkbox-442']: array();
        if( in_array('Technical', $maillist )){
            $url = 'https://escapehunt.us19.list-manage.com/subscribe/post?u=87a3f3fa58cd92b3eee996143&amp;id=4fa993ecd1';
            $response = wp_remote_post( $url, array(
                'method'      => 'POST',
                'timeout'     => 45,
                'redirection' => 5,
                'httpversion' => '1.0',
                'blocking'    => true,
                'body'        => $target_data,
                )
            );
        }
        if( in_array('EscapeHunt', $maillist )){
            $url = 'https://escapehunt.us19.list-manage.com/subscribe/post?u=87a3f3fa58cd92b3eee996143&amp;id=214fa81b19';
            $response = wp_remote_post( $url, array(
                'method'      => 'POST',
                'timeout'     => 45,
                'redirection' => 5,
                'httpversion' => '1.0',
                'blocking'    => true,
                'body'        => $target_data,
                )
            );
        }
    }
  
}; 
         
// add the action 
add_action( 'wpcf7_mail_sent', 'cf7_action_wpcf7_mail_sent', 10, 1 );