euc_jp and euc_kr seem to be backward (that is, codecs translates them to the _ version, instead of translating the _ version to the - version).  I worry that there might be other deviations from the standard email names.  I would suggest we pull the list of preferred MIME names from the IANA charset registry and make a test out of them in the email package.  If changing the name returned by codecs is determined to not be acceptable, then those entries will need to remain in the charset module ALIASES table and the codecs-check logic adjusted accordingly.

Unfortunately the IANA registry does not list MIME names for all of the charsets in common use, and the canonical names are not always the ones commonly used in email.  Hopefully the codecs registry is using the most common name for those, and hopefully if there are differences it won't break any user code, since any reasonable email code should be coping with the aliases in any case.

Ezio, if you want to steal this one from me, that's fine by me.