i love this. A startup I was at during early COVID times got acquired into Hewlett Packard Enterprise, so we all became HPE employees with HPE addresses. There was a similar form there to request "ryancnelson"@hpe, etc... One of my co-workers got cute and asked for "root@hpe.com" .... And boy, there's a lot of cron jobs running at HP.
I’m confused why cron jobs would be sending emails to root@hpe.com?
When I set this sort of thing up, I'd get myself a hostname on an internal subdomain. But that was a truly miserable experience. It was a multi-stage form submission on a server I imagine to be the closest possible relation to an actual potato. It was soul-destroyingly slow. Alternatively, you could just pretend your machine was hpe.com - the hostname was valid, even if the IP was totally wrong, and the SMTP server would accept it.
My guess is that there was a bunch of stuff that pre-dated the HP/HPE split and they took the quick and dirty option whenever the old internal domain name got yanked during the changeover. And if your process runs as root, you get root@hpe.com and hope there's something in the subject/body to identify the specific machine.