Email authentication
The great folks over at MailChimp have compiled a list of which authentication methods (DK, DKIM, SPF and SenderID) are in use at which ISPs.
Good stuff and very clear showing who is using what authentication.
Related Posts
Predictions for 2008
I did not have a lot of predictions for what will happen with email at the beginning of the year so I did not do a traditional beginning of the year post. Over the last 3 – 4 weeks, though, I have noticed some things that I think show where the industry is going.
Authentication. In January two announcements happened that lead me to believe most legitimate mail will be DK/DKIM signed by the end of the year. AOTA announced that approximately 50% of all email was currently authenticated. They did not separate out SPF/SenderID authentication from DK/DKIM authentication, but this still suggests email authentication is being widely adopted. AOL announced they will be checking DKIM on their inbound mail. I expect more and more email will be DKIM signed in response to this announcement.
Filtering. The end of 2007 marked a steady uptick in mail being filtered or blocked by recipient domains. I expect this trend to continue throughout 2008. Recipient domains are rolling out new technology to measure complaints, evaluate reputation and monitor unwanted email in ways that tease out the bad actors from the good. This means more bad and borderline email will be blocked. Over the short term, I expect to see more good email blocked, too, but expect this will resolve itself by Q2/Q3.
Sender Improvements. As the ISPs get better at filtering, I expect that many borderline senders will discover they cannot continue to have sloppy subscription practices and still get their mail delivered. Improved authentication and better filtering let ISPs pin-point blocks. Instead of having to block by IP or by domain, they can block only some mail from a domain, or only some mail from an IP. There are a number of senders who are sending mail that users do not want mixed with mail that recipients do want. Right now, if there is more mail that recipients want in that mix, then ISPs let the mail through. This will not continue to happen through 2008. Senders will need to send mail users actively want in order to see good delivery.
Less is more. A lot of other email bloggers have talked about this, and I will echo their predictions. Less email is more. Send relevant mail that your customers want. Target, target, target. Good mailers will not send offers to their entire database, instead they will send mail to a select portion of their database.
Feedback loops. Use of feedback loops by recipient domains will continue to grow.
Mobile email. More recipients will be receiving email on mobile devices.
Suggestions for 2008
DKIM "i=" vs "d=" and Reputation
This really should be part seven of a twelve part series or some such as it deals with an aspect of DKIM that’s really important, but is way down in the details of implementation. (dkim.org is a reasonable place to start for a general overview of DKIM).
There’s an apparently endless thread on the DKIM-SSP spec development mailing list at the moment about the differences between two fields in a DKIM signature that could be used to tie a senders reputation to. Several ESP delivery folks asked me to explain what everyone was talking about, and this post is a first cut at that.
“i=” vs “d=”
There are two possible fields in a DKIM signature that could be used to identify the sender of a message, and so to tie a sender history and reputation record to. They are the so-called “i=” and “d=” field, from the syntax used to include them in the signature.