In the early days of email, getting junk messages into the hands of recipients wasnt difficult. The real challenge was getting a list of valid email addresses to hit. Those lists were sold on underground forums and passed around on CDs among spammers. Junk email filters were in their infancy and not very effective.
There are so many techniques and so much to know about fighting SPAM. What widely used techniques and technologies are available to Administrator, Domain Owners, and End Users to help keep the junk out of our inboxes?
We're looking for an answer that covers different tech from various angles.