This article explains how to set up email authentication using DKIM and SPF so that your MailChimp newsletters are not categorized as spam.
Determining the Values Required for Creating the DKIM and SPF Records
Log in to your MailChimp account.
Click on your profile name in the menu bar at the top right and select Profiles.
Click Settings, and then click Verified Domains.
Click the View setup instructions link.
Note the information required to configure the DKIM record and to create the SPF record.
Configuring the DKIM Record
To configure the DKIM record required for MailChimp, you will need to create a CNAME record in the Control Panel.
Enter the value k1._domainkey in the Host field. In the Value field, enter the value that you have from the previous steps.
Creating an SPF Record
Create an SPF record in the Control Panel that contains the value you found in the first steps.
You can find more information here about creating an SPF record.