What technology is utilized to confirm the authenticity of outgoing mail using a public key?

The choice related to utilizing public key technology to confirm the authenticity of outgoing mail is DKIM, which stands for DomainKeys Identified Mail. DKIM is an email authentication method that allows the receiver to check that an email was indeed authorized by the domain owner and that the email content has not been tampered with during transit.

In DKIM, a digital signature is added to the header of an outgoing email. This signature uses the sender’s private key to encrypt specific parts of the email. Upon receipt, the receiving mail server can use the corresponding public key—published in the domain's DNS records—to decrypt and verify the signature. If the signature matches, the email is considered authentic and can be trusted.

This mechanism ensures the integrity and authenticity of the email without revealing the private key, thereby confirming that the email originated from a legitimate source and has not been altered in transit.

Other technologies like SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting & Conformance) work in conjunction with DKIM and have their own roles in email authentication, but they do not utilize public key cryptography in the same way DKIM does. SMTP (Simple Mail Transfer Protocol), on the other hand, is the protocol used for sending emails