Hi,
There was a problem with the HTML emails not been sent in version 8.1
We made many stability fixes to email functionality in autumn 2016 (8.2 version).
Patching these types of problems is very difficult and time consuming so its not a good option.
At this point we would suggest to update to 8.3, that is the released version
Old emails might go out after updating, so deleting the email queue for old unsent emails might be necessary to avoid it.
Kind Regards,
HnasaWorld Team