Hi,
We just released HikaShop 2.2.2 and I submit a patch today which will add the dir="rtl" depending the current loaded language. The new package with the patch should be available soon.
When you edit an HikaShop email, you don't have access to the "html" or "head" tags. They are added by HikaShop itself.
That why the best for this feature, is to be integrated directly in HikaShop.
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.