Beware the oversimplification

stencil.linkedin-post-7
Setting up a DMARC record is the easy bit. Anyone can publish a record in DNS that will trigger reports to them. The challenge is what to do with those reports and now to manage them.
DMARC is a complex protocol. It builds on two other protocols, each with their own nuances and implementation issues. I’ve written in the past about what DMARC is, what you need to know to decide if you’re ready for DMARC and walking through whether or not you should publish DMARC. I’ve done talks where it’s taken me 20 minutes and dozens of slides to set up the context for explaining DMARC. Even experienced email folks can have moments where we get confused by some of the nuances.
DMARC is not a passive protocol. DMARC is an active protocol. Even with a p=none record, there is ongoing monitoring and work. Why consume reports if you’re not going to monitor them? The reports are there so that senders can monitor their authentication. If you’re not monitoring, then why waste cycles and bandwidth to receive them? Do you even know if your mail aligns? Can your mail server handle emails with attachments larger than 10MB? Does your mail server block .zip files? All of these things can cause your mail to be rejected and you won’t receive reports.
Postmark has a great post on DMARC and even has some examples of reports.
I know, I know, there’s a lot of fear mongering about how any company not publishing DMARC isn’t going to get to the inbox. We’re not there, yet. We likely won’t be there in the next few years. We may never get there. In any case, it’s much better to actually think about what you’re going to do with DMARC Plus, ISPs are already checking for DMARC style alignment even in the absence of a DMARC record. You don’t have to publish DMARC for this to happen, it already does.
I’ve said it before: publishing a DMARC record is a good idea. But every company needs to take minimal steps to figure out if publishing DMARC, even just to receive aggregate reports, is the right thing for them. It’s not right for every company or domain at the moment.

Related Posts

DMARC=BestGuessPass

Looking at the headers within the mail received with my Office365 domain I see dmarc=bestguesspass.  BestGuessPass?  That’s a new.
Authentication Results
A few days after seeing dmarc=bestguesspass, Terry Zink at Microsoft posted an explanation. Exchange Online Protection, the filtering system for Office365, is analyzing the authentication of incoming emails and if the domain is not publishing a DMARC record, EOP attempts to determine what the results would be if they did.  If an email is received that is not authenticated with either SPF or DKIM, the dmarc= results show none just as it always had.  DMARC=BestGuessPass will appear if the message is authenticated and the matching authenticated domain does not have a DMARC record.
Having this information is helpful to see what the results would be before setting up a DMARC record. If you are seeing dmarc=bestguesspass when your mail is sent to an Office365 address and you are considering DMARC, the next step would be to publish a p=none DMARC policy and begin to document where your mail is being sent from.  P=none will not have an impact on your delivery and asks the receiving mail server to take no action if a DMARC check fails.  Once you have setup SPF and DKIM for your mail, p=none policy gives you the ability to begin receiving failure reports from receiving mail servers when unauthenticated mail is sent from your domain.

Read More

Should you publish DMARC?

secure_email_blogI’ve been hearing a lot lately about DMARC. Being at M3AAWG has increased that. Last night we were at dinner and heard from the next table “And they’re not even publishing DMARC!!!!”
I know DMARC is the future. I know folks are going to have to start publishing DMARC records. I also know that the protocol is the future. I am also not sure that most companies are ready for DMARC.
So lets take a step back and talk about DMARC, what it is and why I’m still a little hesitant to jump on the PUBLISH DMARC NOW!! bandwagon.

Read More