They strike me as a possible spam place. If you go to signup with them, they want you to import your email addresses before the account is even setup!
I checked this place out before, but didn't sign up because I didn't like their TOS. I forgot about it, and recently signed up with them, but their TOS were changed. Before, it said that any info you gave them to signup, was theirs to use, rent, give away or sell as they pleased. Of course, to sign up, they required your name, address, phone number, and another email address you already had.
I think they want your address book real bad, asking you to import your addresses before you even have completed the signup with them. I'm never going to use it for real business, or friends, just as another spam signup address. Just in case, the only addresses I'll put in the address book there will be ones saved from spam, LOL.