DKIM: what it's not

An ESP twittered this past week about their new DKIM implementation going live. They were quite happy with themselves. Unfortunately, in their blog post, they mentioned 3 things that DKIM would provide for their customers, and got it wrong on all 3 points. Their confusion is something that a lot of people seem to get wrong about DKIM so I thought I would explain what was wrong.

  1. “[M]essages are affirmatively identified as coming from our servers…” DKIM isn’t necessary to affirmately identify mail as coming from a particular server or IP address. In fact, one of the major benefits of DKIM is that it allows sender reputation to be independent of IP address reputation.
  2. “Messages are more likely to be delivered to the inbox rather than the spam folder.” Not necessarily. The presence or absence of a valid DKIM signature is unlikely to increase inbox delivery on its own. Having a valid DKIM signature and a good reputation for that sender may result in better inbox delivery. The ISPs aren’t currently, are are unlikely to, offer preferential inbox delivery just on the basis of a DKIM signature.
  3. “Larger ISPs are heading towards requiring a DKIM signature on all incoming email. We are providing this feature now to avoid any issues in the future.” This is currently untrue and it is extremely unlikely that any ISPs will ever *require* a valid DKIM signature on all incoming email. The internet is just too large and too varied for ISPs to expect that all wanted mail will be DKIM signed.

DKIM is a way to authenticate email. Senders with good reputation will be able to take advantage of that reputation no matter what IP address they send mail from.
Senders should encourage ESPs and MTA vendors to implement DKIM signing sooner rather than later. However, DKIM signing alone will not improve delivery.

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DKIM implementation survey: prelim results

First off, I want to thank everyone who participated in the DKIM implementation survey. This week has been pretty hectic so far, so I haven’t had a chance to actually dig down into the data from the survey, but I thought I’d post some preliminary results.
The ESP survey had 45 respondents. 30% of those sent more than 15 million emails a month.
Of all the respondents: 40% are signing with Domain Keys, 51.1% are signing with DKIM.
Of all respondents: 79.5% are signing with Domain Keys and 78.8% are signing with DKIM to access services (whitelists or FBLs) provided by the ISPs.
50% of those not signing with Domain Keys are not doing so because customers have not requested it.  61% of those not signing with DKIM are not doing it because of technical difficulties with deployment.
The ISP survey had 16 respondents, with 37.5% handling less than 500,000 mailboxes and 18.8% handling more than 15 million mailboxes. 75% of respondents said they are not checking Domain Keys on inbound mail. 56% said they are not currently checking DKIM on inbound mail.
Only 10 ISPs answered the question if they plan to check either Domain Keys or DKIM.

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DKIM implementation survey

DKIM has been a hot topic of discussion on some of my mailing lists today. One of the open questions is what is holding up adoption of DKIM. I have my own theories, but thought I’d throw out some questions to see how ESPs and ISPs are currently using domain based reputation.
I have set up two surveys one for ESPs and one for ISPs. Responses are anonymous.
I’ll collect responses for a week and share the results.

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New Delivery tools

A couple nifty new delivery tools were published over the weekend.
Mickey published Bounce P.I. where senders can paste in an error message or bounce and it will tell you what filter generated it. If the rejection is unrecognized, it will flag the message internally and it will be researched to see if the filter can be identified.
Steve has a new tool at the DKIMCore site. The key generating tool and the record checking tool have been up for a while. This weekend, though, he published a tool to check the validity the DKIM record published in DNS. Tool output shows if the record is valid, the version and the public key.

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