A good way to see how an API is used is to look at the web interface and using chrome debugger tools to see the calls.

I was able to get spamchecks with this POST below, note that the "translations" is required, this probably shouldn't be the case.
POST URL: https://mail.smartertools.com/api/v1/settings/sysadmin/antispam/spam-checks
POST DATA, Content-type: application/json

{"searchParams":{"skip":0,"take":"10000","search":null,"sortField":"name","sortDescending":false},"translations":[{"key":"CYREN","translation":"Cyren Premium Antispam"},{"key":"DECLUDE","translation":"Declude"},{"key":"DKIM","translation":"DKIM"},{"key":"DOMAINKEYS","translation":"Domain Keys"},{"key":"MESSAGESNIFFER","translation":"Message Sniffer"},{"key":"REMOTESPAMASSASSIN","translation":"Remote SpamAssassin"},{"key":"SPAMASSASSIN","translation":"SpamAssassin-Based Pattern Matching"},{"key":"REVERSEDNS","translation":"Reverse DNS"},{"key":"NULLSENDER","translation":"Null Sender"},{"key":"SPF","translation":"SPF"},{"key":"HONEYPOT","translation":"Honey Pot"}]}


So for example, I opened my chrome debugger window. Navigated to the spam checks section, then I was able to see how the interface made that call. If you replicate what the interface does best you can, you should get the same results out of it.