How does facebook know your past email contacts?

[.]

I received an invite from my brother, and on the bottom of the email/invite they have, "Other people you may know on Facebook". It shows people I used to talk to on my email account, but have removed all traces of them from my account. So, how do they know that talked to them or even knew them?

[Read My ☆Lips☆]

Your brother may have them as contact on his Facebook or his email contacts. Since your brother is befriending you, Facebook is suggesting that you might know them too.

[dannyboy9780]

Because it connects and finds users from your email address i think thats how it works