How can SPF/DKIM pass, and yet DMARC fail?

DMARC introduces the concept of "Identifier Alignment" to the world of email.  The concept is needed as SPF and DKIM are stand-alone technologies capable of associating a domain with a piece of email. When a receiver uses SPF, the receiver looks at the domain found in the RFC5321.MailFrom to figure out where to look for…
dmarcian
12 October 2015
Industry News

More Yahoo domains move to p=reject

Yahoo is placing ymail.com and rocketmail.com into p=reject on November 2nd. This information is being provided to give people and companies time to prepare, as the #1 piece of feedback from when Yahoo moved yahoo.com to a p=reject was that Yahoo didn't let the Internet know about the move in advance. Hopefully, this announcement will…
dmarcian
12 October 2015

Broken SPF…what does it mean?

People sometimes write in and ask "what is the impact of a broken SPF record"? The net effect of a broken SPF record is that receivers can't reliably use SPF to determine the legitimacy of the domain's email.  *Some* receivers might ignore the broken parts of an SPF record and keep checking, but out of…
dmarcian
10 October 2015

PTR mechanisms in SPF records

If PTR mechanisms are detected, the current diagnostic output is: Warning: PTR mechanisms SHOULD NOT be used and cannot be resolved using this diagnostic tool.  More info at <this page!>. What does the PTR mechanism mean?  When an email receiver gets a piece of email and the PTR mechanism is in the sender's SPF record,…
dmarcian
9 October 2015
dmarcian Tools

Meaning of “WARNING: No A or AAAA records found”

If you publish an SPF record and use the a mechanism, but your domain doesn't actually have an A record in place, then you'll see this warning. Here's a sample SPF record that contains the a mechanism (the a is in bold): v=spf1 a include:_spf.google.com ~all The A DNS record is how you use the…
dmarcian
8 October 2015

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 +…
dmarcian
5 October 2015