This was mine:
You're officially in the reservation queue for Steam Machine 2TB
I assume if you do not put the 2TB, you'll hit any of the variations you have selected... unless they change it.
I passed on the reservation. 2TB is the worst variation because you're paying the $300 extra for a 2TB nvme drive, and you don't get the controller for $80 that retails for $100 and ebays for $300 (not that i've ever sold anything on ebay.. but if i'm getting f'd by memory prices I want my purchase to be worth it vs the value. 2TB nvme drive for $300 more than a 512gb one is absolutely not worth it even with modern prices.
edit: another one you should probably look for is the 72 hour timer email
Please confirm your Purchase Information for Steam Machine 2TB
is the second email I got letting me know I had the 3 days remaining.