Right with you on Fastmail, it's excellent. Just wondering though where do you feel you can't use Firefox? As far as I know it runs on all major platforms even if the rendering engine on iOS is still Safari.
I find on iOS it just isn't as well integrated as using Safari.
Also, apps.
Edit: I am trying it again and it seems a lot better integrated than when I last tried - you can set it as your default browser! Is there a reliable way to block ads, though?
