What You Need to Know About DomainKeys
By Julie Graham / August 25, 2015

DomainKeys (DK) and DomainKeys Identified Mail (DKIM) are email authentication technologies designed to identify legitimate senders of email. Email authentication technologies like DK and DKIM were developed to prevent “spoofing,” the nefarious practice whereby anyone sending an email could potentially use your domain in the “From”: address for their message.

DK and DKIM help prevent spoofing by cryptographically “certifiying” that:

  • You are the actual sender in the “From:” address, and;
  • What you sent has not been altered along the way.

Is one better than the other?
DK and DKIM are similar, but they are slightly different. In 2004, DomainKeys was introduced by Yahoo! first, as a tool to combat spoofing. The DKIM standard was published at about the same time, as an extension of DomainKeys. While some among the email community still prefer DomainKeys, DKIM is generally more widely adopted due to its broader capabilities and backwards-compatibility with DomainKeys. We expect receivers to gradually move toward DKIM as the dominant standard. The good news is that it’s easy to implement both so you cover all your bases.

How does DK/DKIM affect deliverability?
DK/DKIM is not required by ISPs. As such, not having your messages signed using DK/DKIM probably won’t have a negative effect on deliverability – but it won’t have a positive one, either. Remember, it’s your mailing reputation that ultimately determines whether your email reaches the inbox or the junk/bulk folder. Associating an email message with a signing entity enables ISPs to more easily identify good or bad senders, so DK/DKIM can act as a favorable mark toward your mailing reputation.

There are two primary reasons you should care about DK/DKIM:

  • Introduction of DK/DKIM technologies represent a movement on behalf of ISPs to look at domain-based reputation. In the past, your mailing reputation was associated solely with your sending IP address.
  • DK/DKIM allows reputation portability, since your sending domain can follow you to whatever IP address you may be sending from in the future.

Getting started with DK/DKIM
In an environment where reaching the inbox is becoming harder and harder, every positive action associated with your sending improves the likelihood that your email will reach the inbox. That’s why, if you are sending from a dedicated IP address with BlueHornet, we highly recommend authenticating your messages with DK/DKIM.

DK/DKIM authentication is available for all BlueHornet clients who send from a dedicated IP address. To implement DK/DKIM and SPF/Sender ID on your BlueHornet account, just contact your Account Manager.


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