How does Plaxo determine "People you may know"?

[edoe]

I was just invited by a friend to Plaxo, based on my email.
So I filled in an alias name and registered just to check out the site.

Now I am quite astonished to actually find a collection of (old) acquaintances under the "People you may know" link.

How does Plaxo determine the connection between my Email and these Names, Emails (and Pictures)?
There seem to be two possibilities:
1- Plaxo bought databases from other portals (Xing?) that collected these connections (I cancelled my account there, and didn't allow them to trade my data).
2- Plaxo read my email clients address book (without asking - How? Through Javascript?)

Each of these possibilities seem equally frightening to me - and I am willing to spend time and resources to clarify these questions.
Any hints?

[bataspur]

Oh, is it so?

Then this might be a serious loophole. And although I registered onto Plaxo only today initially attracted, this might come in as a roadblock from being a heavy user, unfortunately.

[jbiddle8]

I was wondering the same thing. Any help would be greatly appreciated.

[moolah]

Those kinds of things look at email domain, company, city, school etc. I only know this from FaceBook but i get a lot of people I used to know.