We have created a custom XML feed, using a Wordpress page template, to load in custom posts. Here is our page: https://www.kortingvandedag.be/feed-copernica/
We use this for our email marketing. But now there is an issue, with this file being loaded in too often. Appearantly, the Expire Header is the following for this file:
Expires => Thu, 19 Nov 1981 08:52:00 GMT
Which is far in the past. According to support at our ESP, this should be 1 or 2 hours in the future.
I've used this website to check the Expire header: http://www.webconfs.com/http-header-check.php
We are running WP Rocket on our website and I've tried adjusting the ExpireByType codes, but it didn't work.
Any suggestions on how can I change the expire header for this specific page/file/XML feed?