I just learned something interesting about Facebook.

I got an invitation to join from a friend of mine I knew from Boston. He now lives on the west coast.

At the bottom of the email it had a section of ‘Other people you may know on Facebook.’

And it listed:
two people I know from my church
one person who is another dog walker I see at the park
a friend of the family who is recently graduated from college
a woman who was on the volleyball team with me a million years ago (who I didn’t even remember knowing!)
one of my dog walking clients

It’s absolutely astounding that FB figured out I know these people. And yet it did NOT mention my college roommate who I know has a FB account.

So I started poking around. What do they have in common that my college roommate does not?

I finally found the answer when I went digging into my own inbox in Outlook and found an email from the volleyball team member from years ago.

All the people have two things in common:

• They have all sent me an email at the same address my friend sent the invite to AND
• They all have free web-based emails as their addresses (hotmail, gmail, aol, etc.)

My college roommate, on the other hand, has also sent me emails BUT has an email account on her husband’s own domain, not a free service.

So here’s what I deduced:

1. When my friend sent me the invite, he made my email address known to Facebook.
2. Since those people have free email accounts, anyone they’ve ever addressed an email to is public knowledge as far as aol, gmail, hotmail, etc. is concerned.
3. There must be some backdoor shenanigans going on in the cyber world in which aol, gmail, etc. sells that information. It wouldn’t be hard for a program to sort through all that and find everyone who ever sent an email to me, and compile a list for “You May Also Know (this person).”

And since Gmail and Facebook are both owned by Google, this is not a far stretch.

Interesting…and a little scary.

Here’s a related thread:
Facebook Friend Suggestion: How Does it Know???