Can't attach .html files, at least it wasn't in the accepted attachment list that I remember seeing. Doesn't matter, linking to the file directly with the http:// URL in a browser forces it to look at it as an html file anyways so the extension is irrelevant. the extra .txt was because of my local machine.
The reason I did this was because I have a new phone that has net access with a typical mobile phone web browser interface, IE it tries to force you to go through the providers portal at every turn. To keep my MB usage down so I can use the cheaper monthly rate for the few things I want to be able to do I'm going to need to create a .html that has the handful of links on it that I want perhaps a little java script. The built in favorites function on the phone is actually a web interface through the provider, with lots of graphics downloads (that you can't even properly see anyways) that suck MB's with no useful information returned. This was just a quick test to verify basic HTML functionality. I don't have any web space I can toss a link so I did it via an attachment here for a quick test.