Adoption Email Scams

I was asked how we could tell these emails were adoption scams. In our case these were "parents" trying to give us their children. I've been online all morning trying to find an article to display here, but those are more related to people actually approaching you, taking your money, and then just disappearing before the due date.
The first thing I noticed with these emails we received is that they sound just like those email scams that say something like: I need to get this money, but I can't deposit it to my account. I will deposit it to your account if you will pay me $5000 to do so, but then you will receive $50,000. I'm sure we have all received them.
The biggest clue has been the way they talk. Clearly these emails are not coming from America. Here is just a few excerpts from these emails:
-well my intentions are to make sure this lill girl is in good condition with a loving family before I go.
-i will like to know more about the family who is going to adopt my twins
-all i will ask from God is that he should bless you so much since you have a human feeling to another
-My baby is eight months running now and i really need help.moreover i need a mum for my baby because i will not be able.
The other thing I have noticed is that the emails come about the same time that Dallon emails us from Africa. I am sure there really is birth mothers out there who can't sleep at night and that is when they are online, but to me these emails just seem to scream "Nigerian Scam."