Hi,
Regarding your message and the paypal email, the only thing I can say is : I do not understand anything.
I can't say that all if working fine in the paypal side, otherwise you wouldn't receive a 500 error during the IPN validation.
So I thinking that they do not understand the problem at all.
And.. Why are they talking about the email notification ?
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.