Sending HTML email

I’m trying to send an HTML email (Mutipart-Alternative MIME format) to the requestor upon resolution of a ticket. I’ve created a Scrip, that’s triggered by an ‘On Resolve’ condition, and a Custom Template but I’m not sure how to get RT to properly interpret the mail format.

Is it possible to have RT send an HTML email using a Template? Has anyone done this and if so are there any examples? Or is there perhaps another approach besides using the Templating feature?

Any help will be appreciated. Thanks.