Email Message Generation Techniques

System

I've been asked to come up with a standard for generating workflow email messages for this project.

I have seen a number of techniques for generating email and I am wondering if people can list the pros and cons of the methods they are using. The ways I know of include:

-Generating the entire message from Perl - embedding HTML in Perl can lead to code that is difficult to read
-Using custom (html) configuration files with token substitution - this can lead to a large number of configuration files
-Using presentation templates - this also would seem to result in a lot of files and could be considered overkill

What other approaches are available? Is anyone using Job XML with XSL?

I guess I'm leaning towards the config file with token substitution, which I've had good luck with on previous projects, but I'm wondering what the consensus might be. Of course there would have to be some logic around the config files, but the less HTML mixed with Perl, the better (at least that's my opinion).

For better or worse, a lot of environments let "config" changes through to production a lot more easily than "code" changes, so if the work is done in TPL/Perl/PM it can be harder to get fixes in than if it's done with config files/xsl.