It doesn’t matter if it is from an E-mail, from an “investor”, from a PTC Site, from a BitCoin Faucet; if you are asked for Money / BitCoins to receive Money / BitCoins, it is a fraud / scam.
I could probably write a book with all of the different reasons and stories of why you are asked to send money (or BitCoins, although it is a form of money) in order to receive a lot more money than the one you are sending, scammers can be extremely creative.
But just as you will not walk over a mined field because it is a “shortcut” somewhere, you should not give away your money like that.
In this regard, trust your intuition. If you don’t feel ABSOLUTELY comfortable with a deal, don’t do it. No matter how tempting it is, don’t do it.
I’m still working in some things, but I have been shocked by how many scams exist in the BitCoin world, but so there are in the PTC world, it’s crazy. Anyway, I still got out the list of good PTC sites for the 2017 if you are looking for something, but I think it is very important that you protect yourself, your time and your resources, all of them are limited for the majority of us making a living in this strange times.