Social networking sites in general only grow through this type of spamming. Facebook was one of the worst offenders in its early days - Hotmail even blocked th

Social networking sites in general only grow through this type of spamming. Facebook was one of the worst offenders in its early days - Hotmail even blocked their invite messages for a substantial period of time. It is no coincidence that many of the sites that use the contact-list/auto-invite feature most aggressively have grown the fastest. Although we might find it objectionable, apparently most users either don't object to it or don't realize that it even happened (my guess would be that hundreds of millions of FB/LI users fall into the latter category).