Brief history of email authentication

Email is huge (largest deployed application on the Internet?) and it takes a long time to change the fundamentals. 2003: First SPF draft 2004: First DomainKeys draft (predecessor to DKIM) 2006: First DKIM draft PayPal begins work with Yahoo on authentication-based model 2007: BITS Email Security Working Group publishes paper recommending TLS + SPF + DKIM for email DKIM RFC published PayPal + Yahoo blocking based on DomainKeys+SPF goes live 2008: PayPal publishes "A Practical Approach To Managing Phishing" 2009:…
5 October 2015


A user once asked: I can't seem to find the answer to this question anywhere on the Internet (it may just be me not fully understanding the standards), so I thought I'd ask you. If I have DMARC set up in my DNS (which I do) and also ADSP (also do), which one takes precedence? I'm also assuming that I am in overkill mode and that DMARC is enough. Your input would be appreciated when you have a moment.…
4 October 2015

What is the difference between SPF ~all and -all?

SPF is all about publishing a list of servers that are authorized to send on behalf of a domain. After writing out a list of servers in the form of an SPF record, the right thing to do is to end an SPF record with something that says "and everything else on the Internet is NOT authorized". The way the above is written is to use the "all" mechanism.  This mechanism matches everything.  By adding a prefix of "~" or…
3 October 2015