Which standard is used to validate signatures in email communication?

The correct answer is DKIM, which stands for DomainKeys Identified Mail. DKIM is a standard that enhances email security by allowing the sender to digitally sign their email messages. This digital signature is then added to the email's headers. When the email is received, the recipient's mail server can validate this signature by retrieving the sender's public key published in the Domain Name System (DNS).

This process ensures that the email has not been altered in transit and verifies that it genuinely comes from the domain it claims to originate from. As a result, DKIM establishes a level of trust between senders and recipients, which helps combat spam and phishing attacks.

In contrast, other options such as SPF (Sender Policy Framework) primarily focus on specifying which mail servers are allowed to send email on behalf of a domain, but it does not provide the ability to validate the integrity or authenticity of the content of the email itself. DMARC (Domain-based Message Authentication, Reporting & Conformance) builds on both SPF and DKIM by providing a mechanism for receiving domains to report back to senders about the authentication status of their emails, but it isn't a standard used for validating signatures directly. SMTP (Simple Mail Transfer Protocol) is the protocol for sending emails but