dkimproxy-sign [options] < original_email.txt
to see a full description of the various options
--method Determines the desired canonicalization method. Possible values are simple, simple/simple, simple/relaxed, relaxed, relaxed/relaxed, relaxed/simple.
--debug-canonicalization Outputs the canonicalized message to the specified file, in addition to computing the DKIM signature. This is helpful for debugging canonicalization methods.