Call and edit templates

Hey guys,
I want to send out a bunch of emails.
I created a template in Mail that I wanna use.
I just need to choose the template and then transport some data ( like the name and some other infos ) from a numbers table.
I know I can create that template also with applescript, but you can’t use rich text in appleScript right ?
So in my case I need rich text.
Is there a way to tell mail to use the template, add some data, and send it out ?

Thanks in advance!