You can trigger a 404 and show the 404 template by using the {redirect="404"}
tag but this keeps the URL as it was entered.
This plugin will force a 301 redirect to the actual 404 URL.
- Replace
{redirect="404"}
with{exp:fourofour:redirect}
. - On your 404 template, force 404 headers by adding
{exp:fourofour:page}
.