To get to the tool, log in and navigate to the Domain Overview. Click on the SPF cell for a domain that has volume, and then click ‘Record Details’.  In the resulting view, select ‘View TMI’.  The reloaded view of the SPF record details integrates DMARC data to show you which of your SPF record entries are in active use for your domain(s), and in what way.  This can help you figure out which old entries in your record might no longer be needed, and it can also help to identify senders you work with who are actually not sending SPF authenticated email correctly.

Please note that this feature only provides reliable feedback on domains for which you have received DMARC data in the past seven days, and in some cases, a seven day period may not be sufficient to suggest that a particular IP range/include/etc can be safely removed.  If not entirely certain, check back on it at a later time to verify the lack of traffic.