cvt_cyrusdb
is used to convert a cyrusdb file between different database backends. Note
that you should not attempt to use the same file for input and output.
Running without any options will list the available database backends.
cvt_cyrusdb
reads any applicable configuration options out of the
imapd.conf(5)
file unless specified otherwise by -C.
note that the file locations are NOT read out of the configuration file,
and must be supplied on the command line.