  Superconducting order parameters that are odd under exchange of
time-coordinates of the electrons constituting a Cooper-pair, are potentially
of great importance both conceptually and technologically. Recent experiments
report that such an odd-frequency superconducting {\it bulk} state may be
realized in certain heavy-fermion compounds. While the Josephson current
normally only flows between superconductors with the same symmetries with
respect to frequency, we demonstrate that an exchange field may induce a
current between diffusive even- and odd-frequency superconductors. This
suggests a way to identify the possible existence of bulk odd-frequency
superconductors.
