Why oh why does this happen? Basically a few of my friends will send me a text message and we'll have a conversation. Later on I'll get another text message but it won't be grouped with the old text message even though its from the same person. If I click on the "contact" button at the top right of the screen, I can see where it comes from. One of them comes from their actual phone number and the other is from an email address. Explain?