Which of the following is considered best practice for preventing e-mail spoofing?

The best practice for preventing e-mail spoofing is to use cryptographic signatures. E-mail spoofing is a technique that involves forging the sender’s address or identity in an e-mail message, usually to trick the recipient into opening a malicious attachment, clicking on a phishing link, or disclosing sensitive information. Cryptographic signatures are digital signatures that are created by encrypting the e-mail message or a part of it with the sender’s private key, and attaching it to the e-mail message. Cryptographic signatures can be used to verify the authenticity and integrity of the sender and the message, and to prevent e-mail spoofing5 . References: 5: What is Email Spoofing? : How to Prevent Email Spoofing