How can you prevent SMTP spoofing?

Implementing SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) is crucial in combating SMTP spoofing, which involves falsifying the sender's address to make an email appear as if it is coming from a trusted source. SPF allows domain owners to specify which mail servers are permitted to send emails on their behalf through DNS records. This helps receiving mail servers verify the authenticity of the sender's IP against the domain's authorized IP addresses.

DKIM enhances this process by adding a digital signature to the emails, which the receiving servers can use to check if the email content has remained unchanged (untampered) and whether it originates from a legitimate source using the sender's public key. Together, SPF and DKIM create a strong defense against email forgery assaults aimed at tricking recipients or bypassing spam filters.

Encrypting email with SSL/TLS does protect the content during transmission but does not address the issue of spoofed sender addresses. Limiting email attachment sizes and requiring two-step verification are good security practices but do not directly prevent spoofing techniques.