I collect these into a database I run locally out of a bad habit I had as a teenager. Back in the AOL days you could 'Email-bomb' someone, and rightfully it sounds exactly like it is -- you'd just send them tons and tons and tons of email.
Well, turns out - that's pretty easy to detect and block. So I came up with a better way, a more permanent way; and probably the reason so many people see their email address as a private/privacy thing now -- You simply submit their email address to every known spam address in existence.
Now, you've got an infinite amount of spam being thrown their way, 24/7, at super high volumes, for essentially - what is the entire lifetime of that account. I haven't done it in the past 20 years or so, and I don't have any of my old 'progz' for it, but I figure one day when I need it again, it will be invaluable.