"Our headquarters are located in Melbourne, Australia with servers at New York Internet and QuadraNet in the USA, and at Switch Datacenters in the Netherlands."
"We do not participate in, or co-operate with, any kind of blanket surveillance or monitoring. (We also point out that Australia does not have any equivalent to the US National Security Letter, so we cannot be forced to do something without being allowed to disclose it.)
...
Unless prohibited by law, we will disclose to the account holder when we receive a warrant for their account."
FastMail has servers in the US and is domiciled in Australia, a Five Eyes country:
https://en.m.wikipedia.org/wiki/Five_Eyes
Mass surveillance and powerful security services do not go together with privacy IMHO.