Back in the mid-90s, when I worked for a publishing company and and (snail-)mailing lists were important to me, I would iterate my middle initial any time I signed up for a magazine or registered at a conference.
To this day I regularly receive come-ons addressed to Larry E O'Brien (today: Smithsonian Magazine). The amazing thing is not even that someone's selling a 15-year-old name on their mailing list, it's that someone's been maintaining the list to reflect my move to Hawaii! Additionally, I'm quite certain that I've never bought anything after 1995 where I sent in "E" as my middle initial.
So if you ever buy a mailing list and see Larry E O'Brien, Kailua Kona, in there? Not worth your money.