Fastmail lets you choose: EU or US data region
Fastmail offers EU data region
Fastmail now offers an EU data region, with primary data stored on its own servers in Amsterdam. Users can choose their region at signup or switch in settings. The company emphasizes transparency about data replication, backups, and legal obligations, noting that while EU data is primarily in Europe, replicas and backups are still in the US, and some metadata is shared across all sites.
If what you need is a guarantee that your data remains only in the EU, we don’t have that, and we’d rather tell you directly than let you assume otherwise.