Hello Guo SpicyGum 
By “anonymous email”, do you mean Disposable email address?
If you do, you can add these domains to the blocked email domains setting.
You can find a list here: disposable-email-domains/disposable_email_blocklist.conf at main · disposable-email-domains/disposable-email-domains · GitHub
As a side note, I wouldn’t bother adding the whole list to this setting… From my experience, many spammers use legitimate email providers such as gmail.