How do some sites detect that I'm trying to feed them temporary email when they sign up?

Question

Email

I don't want to receive spam to my main mail, I have to use services to generate temporary mail, and sites don't accept them. How it works?

Answer 1

The domains of "anonymous" and temporary mailers are parsed, sometimes a filter for domain names is also set, because temporary mailbox services use very specific domains that do not carry a semantic load. Quite easy to see, in general.

Answer 2

most likely filter by domains, search for less popular