DomainKeys Identified Mail (DKIM) is a method for email senders to digitally sign email messages in a way that can be verified by email receivers. This allows receivers to verify that the message truly came from the sender, and has not been tampered with. DKIM is intended to address some of the flaws in the existing email system, such as spoofing, phishing, and message tampering. 

Steps to configure a Sending Domain for Customer.io

• Sign in to your Customer.io account as the admin.
• Go to Settings > Workspace Settings.
• Select Email Settings > Add Sending Domain.
• Click Add Domain after entering the Domain, Display Name, and Email Address from which you want to send messages as illustrated below.

Requirements to enable DKIM authentication for Customer.io

You must add four DNS records to the domains you want to use to send emails from your Customer.io account in the control panel of your DNS hosting provider in order to set up basic authentication for Customer.io. The following requirements need to be included for a successful DKIM authentication for Customer.io:

• 2 mx records
• An SPF record
• A DKIM public key provided by Customer.io
• Verify your sending domain from the Email page

Use our free DKIM record lookup tool to validate the published DKIM record.

Enable DMARC for your domains to protect against spoofing. Sign up for a free trial today!

For more information on Customer.io DKIM setup, you can refer to their reference documentation.