I am using Imail Server 10.2

I am receiving ton of spam emails

Whats recommended settings for the Imail Spam filtering

Premium Filter (Confirmed, Bulk, Suspected and Unknown) Enable All or not?

Connection Checks (Verify MAIL FROM Address, Perform Reverse DNS Lookup for Connecting Server, Verify HELO / EHLO domain, Delete Message after , Prefix Subject with:X-IMail-SPAM-Connection) Enable All or not?

DNS Black List (Please send Standard DNS Black List) 

SPF Enable All or not?

SMTP Settings (Allow Remote Mail to Local Groups, Allow Remote View of Local Groups, Check Valid Sender, Auto Deny Possible Hack Attempts, Disable SMTP "VRFY" Command, Require CRAM-MD5 Authentication) Enable All or not?

Please Advice

Thanks

John Martin