Application-specific e-mail template engine

Does anyone have any experience with creating a templating system for
e-mails sent via Rails? Here is what I'd like to do:

1. User selects "Create message" from my application
2. User selects a predefined template from dropdown list.
3. Selected template populates the message field with the template
tags replaced with correct values (replacing <%= @tutor.name %> with
John Doe for example)

The issue I am running into is I am not sure if I can use standard
RHTML or ERB templates to define the Mail templates. If I can, I am
not sure how to replace the <% %> fields with the correct values on
the fly.

If anyone has any experience with a solution like this, I am all ears.

Thanks.

- j

I believe shopify uses Liquid templates for this. If it doesn't,
Liquid would still be a good fit. Executing pure ruby (erb) from
something a user entered is usually not a good thing.

Thanks Rick. I will look into it.

- j