iCloud’s HideMyEmail service generates @icloud.com addresses. Very easy, single click.

Nevertheless, I still use my personal name at lastname dot com for everything for decades and amount of spam is quite tolerable. Rarely it leaks into inbox. It’s even published on my personal web site in plain text.

Most of the generalized aliasing domains get blacklsited. If you are going to do aliasing set it against your custom domains.

From what I can tell: Atlasian and Stackoverflow try to reject you based on your mx records on the domain (which makes that a problem)

There are a few other companies that try to restrict you to gmail or hotmail domains. (Which is even more frustrating)

It's just fastmail.com, that would be insane to blacklist. Also you don't really use these for sending, it's more for signing up for things and online shopping.

It certainly still happens though. [0]

[0] https://www.fastmail.com/blog/the-internet-blacklist/