hyperkitty_import should be more robust to exceptions
When hyperkitty_import reads a mbox, it tries its best to catch all possible exceptions without catching Exception
because it is bad practice. Ideally the underlying libraries would ensure that only a finite set of well documented exceptions are thrown and hyperkitty_import could handle all of them. Unfortunately they do not and an unknown number of exceptions can happen (see #314 (closed), #313 (closed), #316, #317 (closed)) for examples).
As a consequence hyperkitty_import is more fragile than it should be and the import of a mbox will abort whenever an unexpected Exception happens instead of skipping the faulty message.
Edited by Loïc Dachary