most major platforms reject email addresses that are not from major providers. for example creating a deepseek account asks to use a "global provider" and gives GMail as an example. github recently rejected @proton.me. discord does this as well etc
I’ve never, ever, not once, been blocked from registering because I was using a self-hosted domain. I’ve seen plenty of services that block anonymizers, typically with the explanation that they were getting too much spam from there.
