What DNS record type specifies which mail servers are authorized to send emails on behalf of a domain?

The correct answer is related to identifying which mail servers are authorized to send emails on behalf of a domain. The Sender Policy Framework (SPF) is a validation system designed to prevent spam by allowing domain owners to specify which mail servers are permitted to send email. This is implemented in the DNS (Domain Name System) by adding an SPF record, which is technically a type of TXT record but specifically formatted to articulate the sending permissions for the domain.

SPF works by checking the email sender's IP address against the list of approved IP addresses. If the sending mail server's IP is not in the SPF record, the receiving mail server can identify the email as potentially suspicious and act accordingly, such as marking it as spam or rejecting it outright.

Mail Exchange Record (MX) serves a different purpose: it specifies the mail servers that receive email for a domain, not those authorized to send.

The Canonical Name Record (CNAME) is used to create an alias for another domain name but does not have any implications for email transmission.

While a Text Record (TXT) is the type of DNS record used to hold the SPF information, it is important to understand that SPF records specifically define how an email is sent, emphasizing its role in the broader context