I've noticed that when people in my office exchange e-mail with
attachments that have punctuation in the file name, the punctuation
frequently gets removed from the file name - such as with an
attachment named "Firstname, Lastname.doc" somewhere along the way,
the comma gets deleted.

This is a problem because people end-up with 2 versions of the file -
one with comma and one without.

Does anyone know how this happens or what the rules are for
permissible punctuation marks?