[Mailman-Users] Is there a way to change the template files

[Lists]

So instead of the ones being text to make them html?  I have a client 
asking and I cannot find a way to do that.  Ideas?

Example, the verify.txt, subscribeack.txt,  etc. into verify.html and 
subscribeack.html.  They are processed them as and that is not what I 
want.