Hi walteis,
I've tried to do the same thing with the wishlist emails, with the difference that my
emails showed no images at all...
The same goes for the order comfirmation emails - no images also.
But strange enough it works for the send-to-friend emails and for the
invoices which customers can see in their order status.
You can have a look what I've done:
http://forum.x-cart.com/viewtopic.php?t=15757
I've tried your product thumbnail code and I get the same strange error
as you - no image available for the first product, and the rest are ok.
So, one step closer to succes...
Hopefully somebody know what we're doing wrong.