I love sendmail - it offers flexibility (and, with standalone functions, commonality with minimal maintenance) over the years the templates hadn't offered. I understand the templates have come a long way, but I still prefer sendmail most days.

That said... Unless I missed something, there is currently no way to get the emails sent that way to appear on the record to which they belong. It would be nice for that to be added in as an optional parameter on that function. Notes have a parent id option - perhaps a list of maps (record id and module)  to which it should link? Or a string version of this list to pass in... 

Not breaking prior code, not forcing every email that goes out to link, but to allowing for some to appear as a historical record in the record(s) of choice. 

It's not a crisis requirement, but would be a nice to have and wondered if others would like this as well.