I use Google Mail and set up rules about people/firms/potential spam addresses that I don't want to get Spam from.
I use an old ISP (dial-up) email service that I can also Access On line in a Browser and can set up rules there as well.
You can set up Rules on your Mac Mail App to put items in the Junk folder.
9:27 pm Tuesday; April 8, 2014 iMac 2.5Ghz i5 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad