First one: yes, though good UI should prevent it from happening unless the user really intended it (for example I have ~/Documents symlinked into Dropbox, so ~/

First one: yes, though good UI should prevent it from happening unless the user really intended it (for example I have ~/Documents symlinked into Dropbox, so ~/documents could be local-only documents) Second one: no, emails are not filenames, and more generally distinguishability is more important for identifiers. In cases where identifiers like emails need to be mapped to filenames, like caches, they should be normalized.