As a FastMail customer who spends a portion of the year in the US, I am happy to pay to move my data to the EU region, even if they cannot yet fully guarantee all my data will remain outside of US access at this time. Defense and mitigations in depth, over time. We must always start somewhere, and perfect is never the target (as it does not exist).
Agree - small steps always positive here
But whose cloud infrastructure do they use? (I don't know, but it might likely be AWS, GCP, or Azure.)
That it described in the linked post:
We’ve installed our own servers, co-located in a secure facility in Amsterdam, set up by our own engineers.