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Using DomainKeys Identified Mail (DKIM) Sender Authentication


DomainKeys Identified Mail (DKIM) uses a signature-based method for authentication.

An organization may claim responsibility for a domain and messages sent from it by signing each message with a digital signature and by including a public key in their domain. A recipient mail server will request the public key from the sender's Domain Name System (DNS) and attempt to decrypt the digital signature it received in a given message's header. If the values match, the signature is valid, and the message has not been tampered with during transit. In DKIM systems, a pair of cryptographic keys (one public and one private) are generated for use in signing all outgoing messages. The public key is published to domain name servers, and the private key is made available to Act-On's outbound mail servers.

When a message is submitted for delivery, the outbound mail server uses the private key to generate a digital signature for the message. The signature is included in a special message header, and it can be checked by the receiving mail server to authenticate the sender.

DKIM is one of many technologies and methodologies deployed by mail providers to help cut down on malicious and unwanted mail. It is widely used by the biggest services providing mail to individuals and organizations around the world, people and organizations you will likely want to market to. Failing to implement DKIM does not necessarily mean that fewer of your email messages will make into a recipient's inbox, but it is a contributing factor (along with virus/malware scanning, content scanning, and other systems) to your email's overall 'score' which does impact a message's delivery rate.

As part of the configuration of DomainKeys Identified Mail, it is required to set up a real email account called postmaster@<> which is a requirement of Yahoo! to ensure the deliverability benefits of DomainKeys Identified Mail for Yahoo! Mail recipients.

Act-On recommends setting up DKIM for each of the domains you will use in your 'From' addresses.

To setup DKIM for your 'FROM' addresses you will need:

Once you have access to edit your DNS and have created a postmaster@ email address for your domain(s), contact Support with the following information to setup DKIM:

  • The domain(s) to be used in your “From” addresses
  • The chosen postmaster@ address for your domain(s)

Support will send you a DKIM record to add to your domain’s DNS and will confirm your postmaster address so DKIM can be activated for your account.

  • Log in to your Act-On account, and add your Google mail account to the test list by clicking Contacts > Account Lists.
  • Hover over your Test List and select Open
  • Click Edit All
  • Add your name and email address to the list, click Save Changes.
  • Compose a new message in Act-On with the content of your choice. To do this, click the More... button and click Send a Message to This List.
  • A new window will appear prompting you to choose from starting with a Blank Message, Draft Message, an Existing Template, a Sent Message, or you can choose to upload a pre-designed message or create a plain test message.

Note: Content does not affect the results of the DKIM test.

  • Select the appropriate "From" address for your test email. This should be the same that you will be using for marketing emails.
  • Click Tests > Send Test Message to send this message to yourself, and select your Google mail address as the recipient of the test message.
  • Check your Google mailbox for the Act-On test message.
  • Open the message and click on the down arrow next to the word "me": 
  • If DKIM has been implemented, the "signed-by" will match the domain in the "from" address:

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