Description :- The SPF record of gratipay.com include Mandrillapp which you are not using right now, i'm able to add gratipay.com in my account, although a further verification of domain is required but you should know that Mandrillapp allow to send email from a domain if its SPF records point Mandrill server. I have attached a screenshot to proof my concept 1 SPF record found for the domain gratipay.com : "" v=spf1 include:email.freshdesk.com include:spf.mandrillapp.com include:_spf.google.com -all " This is useful in phishing, and this type of vulnerability is news worthy (http://bits.blogs.nytimes.com/2015/04/09/sendgrid-email-breach-was-used-to-attack-coinbase-a-bitcoin-exchange/) Vulnerability Impact Scenario :- Using my own mandrill account I can send email which appears to originate from @gratipay.com Patch :- The patch is pretty simple. Complete your mandrill registration process. This will lock out other mandrill users from sending email that originates from *@gratipay.com. Let me know if you have any other questions. Check Screenshot. Thanks.