this is happened to me twice and i ignored it, assuming it was a scam but thought i'd check.
So i got this whisper in the game with the message, if you are a subscriber and go through my link i'll give you 3million credits, you will get 500 cartel coins and 7 extra days of subscription.
Didn't want to take a chance it was a scam but two different people have sent this to me now.