Sender Policy Framework (SPF) is one method to help detect forged/faked emails, a technique to reduce email spam and “phishing”. This is achieved by creating special DNS records for your domain that lists all authorised mail servers that are allowed to send email on your domain’s behalf. Upon receiving an email from your domain, a recipient server that supports SPF, will look up this list of authorised servers and determine if the email originated from an authorised server. Emails originating from unauthorised servers will then be rejected or at least marked as spam, depending on your settings.