You should call the insurance company to be sure.
Have you tried google-ing his email address? Just to see what comes up. Also try searching for his name, company name etc to see what turns up.
It could be genuine, I'd hate to recieve €800 through Paypal as the fees would be massive. Alternativly, if you source the amount from your credit card, and it turns out to be fraudulent, can't you issue a chargeback with your company to get the money back?
I wouldnt go down the bank transfer route, as thats notorious with scammers. My heart goes out to you though, however sometimes if it seems to be too good to be true, it usually is.