Bypass Advanced Custom Fields acf_form() create/update post functionality

acf_contact_form_head.php

function acf_contact_form_head() {
	// verify nonce
	if( acf_verify_nonce('acf_form') ) {
		
		// validate data
	    if( acf_validate_save_post(true) ) {
	    	
	    	// form
	    	$GLOBALS['acf_form'] = acf_extract_var($_POST, '_acf_form');
	    	$GLOBALS['acf_form'] = @json_decode(base64_decode($GLOBALS['acf_form']), true);
	    	
	    	// validate
	    	if( empty($GLOBALS['acf_form']) ) {
		    	
		    	return;
		    	
	    	}
	    	
	    	$from_field = "field_55ccea67a2a49";
	    	$email_field = "field_55cceafca2a4a";
	    	$subject_field = "field_55cceb5aa2a4b";
	    	$message_field = "field_55ccec4ca2a4c";

	    	$from = $_POST['acf'][$from_field];
	    	$email = $_POST['acf'][$email_field];
	    	$acf_subject = get_field_object($subject_field);

	    	$subject = $acf_subject['choices'][$_POST['acf'][$subject_field]];
	    	$message = $_POST['acf'][$message_field];

			send_mail($from, $email, $subject, $message);
			// vars
			//$return = acf_maybe_get( $GLOBALS['acf_form'], 'return', '' );
			
			// redirect
			if( $return ) {
				
				// update %placeholders%
				$return = str_replace('%post_url%', get_permalink($post_id), $return);

				// redirect
				wp_redirect( $return );
				exit;
			}
			
		}
		// if
		
	}
	// if
	
	
	// load acf scripts
	acf_enqueue_scripts();
	
}

Just add this to your theme's functions.php and insert acf_contact_form_head() before get_header() instead of acf_form_head()