this is an update to this function which is a little outdated now: http://daddyanalytics.com/integrating-contact-form-7-and-salesforce/

contact form 7 to sales force

<?php 
/**
 * Sales force integration
 */

add_action( 'wpcf7_before_send_mail', 'my_conversion' );

function my_conversion( $cf7 ){
        ob_start();                      // start buffer capture

    $submission     = WPCF7_Submission::get_instance();

    if ( $submission ) {

        $posted_data    = $submission->get_posted_data();


            $email        = $posted_data["your-email"];
            $first_name   = $posted_data["first-name"];
            $last_name    = $posted_data["last-name"];
            $phone        = $posted_data["phone"];
            


            
            $post_items[] = 'oid=<YOU OID HERE>';
            $post_items[] = 'first_name=' . $first_name;
            $post_items[] = 'last_name=' . $last_name;
            $post_items[] = 'email=' . $email;
            $post_items[] = 'phone=' . $phone;
            
            $form_name  = $cf7->name();
            $form_id    = $cf7->id();
            //This checks the form ID so you can use custom fields
            if ($form_id == 129) {

                $post_items[] = 'company=' . $posted_data["company"];
                $post_items[] = 'URL=' . $posted_data['website'];
                $post_items[] = '00NA0000007HGfa=' . $posted_data['change'];
                $post_items[] = '00NA0000007HGg0=' . $posted_data['sales'];
                $post_items[] = '00NA0000007HGg4=' . $posted_data['employs'];
                $post_items[] = '00NA0000007HGgE=' . $posted_data['urgency'];
                $post_items[] = '00NA0000000UpU4=' . $posted_data['want'];
                $post_items[] = '00NA0000007HSCO=' . $posted_data['comments'];

                foreach ($posted_data['changeby'] as $key => $value) {
                    # code...                  
                    switch ($value) {
                        case 'Reading books and implementing the ideas':
                            # code...
                            $post_items[] = '00NA0000007HGgK=' . $value;

                            break;
                        case 'Attending seminars':
                            # code...
                            $post_items[] = '00NA0000007HGgK=' . $value;

                            break;
                        case 'Working with consultants regularly':
                            # code...
                            $post_items[] = '00NA0000007HGgK=' . $value;

                            break;
                        case 'None: I\'m too busy working':
                            # code...
                            $post_items[] = '00NA0000007HGgK=' . $value;

                            break;                                                                                
                        default:
                            # code...
                            break;
                    }
                }
            }elseif ($form_id == 280) {
                # code...
                $post_items[] = '00NA0000007HSCO=' . $posted_data['your-subject'];
                $post_items[] = 'description=' . $posted_data['your-message'];
            }
            if(!empty($first_name) && !empty($last_name) && !empty($email) ){
                $post_string = implode ('&', $post_items);
                // Create a new cURL resource
                $ch = curl_init();
              
                if (curl_error($ch) != ""){
                  // error handling
                }
              
                $con_url = 'https://www.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8';
                curl_setopt($ch, CURLOPT_URL, $con_url);
                // Set the method to POST
                curl_setopt($ch, CURLOPT_POST, 1);
                // Pass POST data
                curl_setopt( $ch, CURLOPT_POSTFIELDS, $post_string);
                curl_exec($ch); // Post to Salesforce
                curl_close($ch); // close cURL resource
            }
        
            //var_dump($post_items);
            //var_dump($form_id);
    }
    
    //error_log can e found under wp-content this is being left in becuase this function is a fucker all in all
    //WP_DEBUG needs to be set to true as does WP_DEBUG_LOG 
    /*
      DUMP THESE IN YOUR wp-config.php file
      define('WP_DEBUG', true);
      define('WP_DEBUG_LOG', true);
    */
    $contents = ob_get_contents();   // put the buffer into a variable
    ob_end_clean();                  // end capture
    error_log($contents);            // Write to wp-content/debug.log (enable debug mode to see it).
    
}

Works fine ! Thanks

Glad to have helped :D