The fact that it was sent to 30 teachers in one batch looks like mass emailing. They did not even bother hiding that fact.

The whole thing feels VERY fishy.

Did you google their email address(es) and they key words in the job offer?

Can you get the IP address from the full header of their email? See info below:

a) How to find an IP address http://aruljohn.com/info/howtofindipaddress/
b) How to track it: http://aruljohn.com/track.pl

If you find out that the IP address is from, let's say, Lagos, then you have got your answer.