Greylisting works by recognizing whether an MTA has seen a sender/source/recipient tuple before, and using RFC compliant messaging temporarily blocking mail from that tuple. A real mailer will retry. A spambot has already moved on to another address and won't bother. Using Postgrey my domain's spam load went from >150/day to basically none.
No more spam except for years of accumulated "opt in" emails, that is.
Opt-in is a polite way of saying "Spam". From the sender's point of view, typically a company that you have done business with, it can't be Unsolicited Commercial Email if the sender and recipient have a business relationship, right? Right. Sure. No matter how hard I try to tell vendors that I spend money with not to spam me, I still get email from them that I do not desire. Typically the actual sender is a direct marketing firm. There are many companies that specialize in sending this type of junk mail. These include Yesmail and DoubleClick. I cite these two because they are the first two chronic abusers of my email address that I am going after now that I can see their signal since I've filtered out the other spammer's noise.
There is one particular on line vendor of office furniture that I have bought from twice that insists on having Yesmail send me their latest specials every couple of weeks. Since I recognized that I had done business with this company, I trusted that clicking on an "unsubscribe" link would not set me up for more spam -- this was a real business. So I did. And then I got another email from them a couple of weeks later. So I clicked on the unsubscribe link again. And then another email came. So I got mad and started to dig into where this crap was coming from. It was a simple matter to track it to Yesmail. Yesmail's home page says:
Yesmail helps hundreds of the world's leading marketing organizations leverage e-mail marketing to grow profitable and lasting customer relationships.
Lasting customer relationships are easy when you don't remove people from your lists!
TRUSTe® is an independent, nonprofit enabling trust based on privacy for personal information on the internet. We certify and monitor web site privacy and email policies, monitor practices, and resolve thousands of consumer privacy problems every year.
When these complaints run their course I'll report back about whether I trust TRUSTe.