Hello,
If you use an email override, your modification will not be lost with updates.
Since you're using HikaShop Business, the email edition interface in the backend will do that for you.
Regarding the content, you can build a HikaMarket link based on the data provided in the email context.
The variable "$data->result->product_id" contains the ID of the product ; thanks to that you can use the Joomla router to build a link to the product.
But it might be difficult to build a nice and SEF url except if you hardcode the Joomla menu "ItemId".
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.