Agreed. It's also a technique that's been exploited by people wanting to distribute malicious files
Seriously?
Well then. I am completely, utterly with macropod on this - use underscores. ESPECIALLY if you raise the issue of multiple dots being malicious. Sheeesh. Really? I have been away too long. But then, I NEVER click open files from email. Ever. And when I was working, we locked users from doing it. They had to save files before opening them. So scanning was done at the front-end (incoming email) and at the (sort of) back end (when they saved files).
I still think using dots in filenames is a bad bad idea. Or at least a very poor idea.