A couple of weeks ago some of my friends sent me SMS.ac (IWNL) invites, so I could join the network and send “free” SMS messages. I had joined the network a good while ago and remember making sure that I selected all the privacy options and so on and so forth, but still getting emails from them every so often. I left that account (and the email address registered with it) well behind.
These invitations don’t just get sent to you once, either, they make sure you receive 3 such invitations from each person, regardless of whether this person actually invited you to join SMS.ac. Yes, you read that correctly. When you sign up for an account they apparently ask you for your Hotmail or Yahoo! (IWNL) ID, and if you happen use the same password on your SMS.ac account as your Hotmail / Yahoo! account (who wouldn’t), they login to your email account and “invite” your whole address book.