Spamming, 15 years on
How long do you think an email address can stay in the spam lists ? I just quizzed a bunch of friends about this, one immediately answered "indefinitely". He's right.
Back in 1992-93, my first job was being a trainee at the INRIA. There was no web back then, we actually witnessed its birth (and all we did was shrug). Usenet was the main channel for discussions, and I used to post in a few newsgroups. Spam was exceptionnal, people doing it (generally college kids who didn't know better) were rebuked by people receiving their messages and would even apologize when they would realize what they had done.
By some strange twist of fate, I find myself working again at the INRIA today, some 15 years later. I started on april 2nd. When I first logged on my office machine and looked at my mail, I was very surprised to find about 45 spams in it. Most of them were directed at my own address, rather than at one of the mailing lists I had been subscribed to by default.
I was rather surprised but given the amount of spam we get these days, I figured it was to be expected, since it couldn't be possible that this was because my address was a "once valid" one (since the INRIA has kept the same policy for creating logins and mail addresses, in effect they had "ressurected" an email address that used to exist 15 years ago). Or so I thought. Then I noticed that some of this spam was directed at a host of the inria.fr domain that couldn't possibly be "seen" from outside. It was the host I used to post to Usenet from.
So it really goes like this : create an email adress, post on Usenet or somewhere where it will be harvested, disable the adress, wait 15 years, enable the adress... and watch the spam pour in.