That's good..... as I dont have complaint scenario in my system can you tell me which field you are referring to by 'remark' , what's the component name/view name/contextnode name/attribute name, same info for email field which you want to make as hyperlink.
use below snippet to add subject & body.
CONCATENATE 'mailto:' lv_string '?subject=Test+subject&body=Sent+From+SAP+CRM' INTO lv_string .
Regarding the standard BP_ADDR email activity issue does the outgoing transaction type is standard or custom ?
Regards,
Shobhit