I found this answer elsewhere that will allow maintaining a proper whitelist instead of disabling the entire Top Spammers feed . "You can add Canonical, Inc's ASN to the IPv4 source list and permit outbound. It's AS41231.
In the IPv4 category, click the green Add button at the bottom. Click the Format pulldown and select ASN. Click the State pulldown and select ON. In Source, type in AS41231.
Under Settings, click the Action pulldown and select Permit Outbound. Under Update Frequency, select Weekly.
After you save it, force an Update or wait for it to run at the next scheduled time.
Many enterprises have at least one ASN, so I think it's a pretty good tool to use to automatically maintain an IP whitelist for each organization.
You can use https://bgp.he.net/ to search for ASNs.", /user/ontheroadtonull