Yes, null.0xf.uk can receive emails.
No, null.0xf.uk is a throwaway domain and should be blocked.
You can use MailCheck's free API to automatically block throwaway emails. Read our documentation to get started. No registration required.
A record
104.26.0.114
MX records
mail.mailinator.com.
23.239.11.30
mail2.mailinator.com.
45.33.83.75