Yes, t-online.co can receive emails.
No, t-online.co 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
None
MX records
mx1.privateemail.com
198.54.122.213
mx2.privateemail.com
198.54.122.215