Cleo, I am running a test right now... with the filters I have in place myself, I normally have under 1000 emails left per day that are spam (my ISP mail gets killed with spam, being the single largest ISP in Canada). Before filters, I don't want to even guess, but I will see based on how many end up in the unverified pile.
I got really tired of looking for the one good email in the 100 pieces of shit incoming, and that really frustrated the heck out of me.
At the start of the year I had NatNet turn off almost all of the email accounts I had with them, as well as all the "trickle down" stuff I had from different domains I own. That was a huge contributor to spam, and I got rid of that and most of the bullshit commercial "get your site listed in google" shit disappeared.
After 30 days, if this sucks too much, I will remove it - but so far I am sure not complaining too much
Alex