I have a text file to track sites that broke with NoScript and cookie blocking, and what additional whitelisted domains are reqired.

Fastmail
fastmail.fm
fastmailusercontent.com

Fastmail hasn’t been on .fm since at least 2017 I think, which dates this file to around that time.

Microsoft’s web services still take the cake for most number of third-party domains that are required to log into their services. I think I even need more than when I first checked.