Hi,
You can create a custom item field for that ; but you will need some PHP code in order to read the field and send an email.
The goal of the HikaSerial plugin is to send "serials" (coupon code, gift certificate, etc) to a specific person.
So if you do not generate serials, that plugin will be useless for you.
Using HikaShop and a custom item field, you will need a custom email and a custom plugin.
Because you do not want to send an HikaShop order status to the other email ; you want to send some custom content.
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.