I treat email as an insecure mostly public form of communication.

This is particularly true when most of the people you’re emailing have gmail anyway.

Things like proton mail make no sense to me in that context.

Fastmail works well and has design incentives aligned with the user, I thought they were the best of the options available when I switched.

Agree with your first point, but Protonmail is at least a marginal improvement.

What new laws in Australia are you referring to? I did a quick search and I saw a lot about anti-spam laws (which is great), but how does that affect switching your own domain to fastmail?

The grandparent comment is likely referring to the TOLA Act, which allows Australian police and intelligence agencies to issue for example technical assistance requests to decrypt or otherwise get access to whatever data they want.

As I understand it the oversight is relatively minimal and any company operating on Australian soil can be subject to such a request. Here's their government web page on it: https://www.homeaffairs.gov.au/about-us/our-portfolios/natio...

It passed around the end of 2018 and a lot of Australian companies (e.g. Atlassian) were not fans of it.

I use a combination of Mailo, Mailbox.org, and Runbox with my domains. They have their varying quirks but I am happy with my choice esp. wrt. their host countries.