Yes.
If you go to the Advanced Editor when editing a reply, lower down on the page you will see a Manage Attachments button. If you click on it you'll get an upload dialog. All the supported file types and their max files size are listed in a key blow the controls.
There is probably a better way to get at this list, but I haven't noticed it yet.
What the heck. For practice I'll add a clip from the screen.