spf flattening
SPF flattening is functionality meant to help deal with overly chunky SPF records that contain too many references to too many different service providers or IP addresses.SPF flattening came about to be a solution a very specific problem: That a lot of senders utilize multiple service providers, utilizing business email platforms like Outlook 365 or Google Workspace, CRM tools like Salesforce, ESP tools like Mailchimp, and more. Each of these comes with guidance to add a specific “include” to an SPF authentication record, and if you add enough of these different “includes” from a multitude of providers, you end up with complex DNS records that take far too many DNS lookups to fully process, beyond what is allowed in the SPF specification. Dmarcian indicates that their “SPF Surveyor” was the first tool to help address this problem by reading your existing SPF record, and providing a new, smaller, “flattened” SPF record