Attempting to narrow down the issue @rulzart is encountering.

django_mailbox/transports/generic.py

@@ -1,10 +1,15 @@
+import sys
+
+
 class GenericFileMailbox(object):
     _variant = None
     _path = None
 
     def __init__(self, path):
         super(GenericFileMailbox, self).__init__()
-        self._path = path
+        self._path = path.encode(
+            sys.getfilesystemencoding()
+        )
 
     def get_instance(self):
         return self._variant(self._path)