Mailchimp authenticates through a verified sending domain: add and verify your domain in Mailchimp, then publish the CNAME records it provides (for DKIM, e.g. k1._domainkey → dkim.mcsv.net). This gives DMARC-aligned DKIM so campaigns don’t land in spam.
In Mailchimp: Website → Domains (or Settings → Verified domains), add your sending domain and verify it. Mailchimp then offers domain authentication.
Add the CNAME record Mailchimp provides to your DNS. With DKIM aligned to your domain, DMARC passes even though mail is sent from Mailchimp’s servers.
Verify it resolves:
$ dig CNAME k1._domainkey.yourdomain.com +shortCheck your SPF record now
Open the free SPF checker →Usually because domain authentication wasn’t completed, so Mailchimp signs with its own domain (*.mcsv.net), which doesn’t align to your From domain. Verify your domain and publish the CNAME.
