To find where the template is, Open the Lotus Notes database in the designer by right clicking on the database icon and clicking on "Open in Designer".
This is also useful if you have the Template Name but not the filename.
Open up Other-> Database Resources
Then click on "Icon".
Click on properties and click on the design tab, and then look at the $TemplateFileName property.
The value is the filename on the server.
The $TemplateServerName can be used to see which server the filename refers to.
The $Title field holds the database title and the version of the template after the #2. This can be useful to foind out what version of the mail template a database is using:
7.0.1, 7.02 etc.
The Icon bitmap is also available here.