When attachments are uploaded, their filename does not appear to be validated in any way to be ASCII-compatible. In our country there are several software solutions that people use to type the special characters of our language, and each of the software has it's own, incompatible-with-others way of doing it. And since we can neither ensure our clients do not use special characters in filenames, nor control what software they use to type these characters, we sometimes get attachments with special characters that turn into question marks when uploaded. An attachment with such a filename cannot be opened or backed up, which complicates any restoration process.
It would be great if there was a global configuration setting that allowed to either automatically replace any non-ASCII characters with something else.