Hi,
The problem is that we can't fix anything in our side.
When you use the dropdown it opens a popup and it show you the email content. Like you can see, the images are displayed fine in your editor (managed by Joomla) but once sent, the images links are not working.
It means that your editor removed the absolute links (containing the domain name) from some of the images.
So it's not something related to HikaShop or the content of the email ; but to the editor and the modifications of the email 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.