It is desirable to have a combination of SPF + DKIM (Email related) DNS records in place in the name servers that serve up DNS domain names for a zone. Due to the way SPF works, CWRU is at it's SPF limit, which only allows 10 includes. DNS Zone Delegation allows a vendor to serve up their own SPF+DKIM (and any other) DNS records in support of your application, which then bypasses CWRU's SPF record limit issue.