Right, I agree, and your use of "narrowcolumn" does work with probably very many blogs. Hmmm... I have been thinking about this too...
I just upgraded today to wp-email203 from wp-email202, and now it is easier to install and manage all the file locations, but many of the template choices in the main wp-email.php are now moved to other files. I can easily make the first page display correctly, but all subsequest pages don't work so well with the themes.
Also, in wp-email.php I added the following, but it is not read by the plugin:
<?php include (TEMPLATEPATH . '/sidebar-right.php'); ?>
It seems that TEMPLATEPATH does work, though, because when I change "include" to "print", it does print out the correct path... but it seems not able to parse secondary WP files. I may be wrong, and I will continue to test.
One trick I thought of was to either have a small pop-up window or a DHTML pop-up... either one would not need a template and might be easier to deal with... just a thought. :)