Security - I think Fastmail is pretty good at security, but I don't think there's another firm on the planet that does as well at security as Google. Specifically, I found Fastmail's implementation of 2FA to be a bit lacking. I imagine that a determined attacker would find it easier to abuse their support processes, since Fastmail's support is quite helpful whereas Google barely even responds.

Spam filtering - I have both Gmail and Fastmail. I'd score Gmail 10/10 on spam preventing, and Fastmail at 8/10.

By the way - I told our support team that you told them they were quite helpful. They are pleased to hear that feedback :)

Seriously though, we have been making as much effort as possible to push the account recovery away from being an "agent decides" to following an automated process. We famously got this wrong once many years ago, and have learned from that!

So the fact that our lovely support people are very helpful once they have identified a person does not mean they are pushovers for an attacker.

They genuinely are very helpful. I always get the feeling I'm speaking to a human being that knows enough technology to answer my questions, and has the empathy to try to understand my problem.

I remember on one occasion needing to extract billing info from a number of different accounts that were under one master account. The support explained there was no native solution, but helped me come up with a workaround. That kind of support is sadly missing from a lot of vendors.

I'm very proud of our support team! That's exactly the kind of help I'd expect them to give anybody :)

We are expecting people to pay money for a service which others provide "for free", so we need to differentiate ourselves, and having real humans who not only provide great service, but are located close to the technical teams and can feed quickly back to improving our service is a key differentiator for us.