Hello,
That plugin "order auto cancel" is there to cancel orders after a certain period.
But they are a lot of other possibilities to have "cancel" orders, like "invalid" payment notifications for example.
So you should first try to understand "what" cancel the order and then you'll now why the email is being sent.
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.