Fastmail’s email servers are in the US and the company is in Australia. Both are in the five eyes jurisdictions, plus Australia has some draconian laws (see Assistance and Access Bill, though email itself is generally not a secure enough channel). ProtonMail is in Switzerland, which is better surveillance-wise, but it still complies (as one would expect a company to) with court orders and has disclosed the IP address of an activist due to a court order.
Fastmail supports IMAP, which means you can use any email client on a desktop or phone. ProtonMail does not support IMAP directly on desktops and requires a “bridge application” for IMAP. This is provided for paying customers. ProtonMail does not have any support for IMAP on smartphones, where you’re either left to using the browser or using the ProtonMail app.
Fastmail’s email servers are in the US and the company is in Australia. Both are in the five eyes jurisdictions, plus Australia has some draconian laws (see Assistance and Access Bill, though email itself is generally not a secure enough channel). ProtonMail is in Switzerland, which is better surveillance-wise, but it still complies (as one would expect a company to) with court orders and has disclosed the IP address of an activist due to a court order.
Fastmail supports IMAP, which means you can use any email client on a desktop or phone. ProtonMail does not support IMAP directly on desktops and requires a “bridge application” for IMAP. This is provided for paying customers. ProtonMail does not have any support for IMAP on smartphones, where you’re either left to using the browser or using the ProtonMail app.