Beside the space issue, you also might take care about globbing. If you e.g. "cp *" you won't copy hidden files of the directory, but all inside folders of the directory. If you e.g. "rm *", you'll delete all files, including hidden files. Regarding to the mail addresses I suspect you're using braille. Anybody using a monitor, who isn't aware of some basic rules, could use GUIs instead of a terminal.