Generally you maybe don't want to include mailchimp's MX's in your SPF for your main corp domain, it's common to send such things either from a delegated (in dn

Generally you maybe don't want to include mailchimp's MX's in your SPF for your main corp domain, it's common to send such things either from a delegated (in dns terms) subdomain (e.g: mailings.ui.com which mailchimp can then manage the spf/dkim/etc records for) or more simply by just using one of your other domains..