is there no way of messaging someone directly through ccmixter?!

Actually there is a way, or kind of.
You go to the person profile and select contact -> e-mail (or by URL shortcut: http://ccmixter.org/people/...)

*But* it seems that the person needs to share his/her email address. For instance, if I try to message you I get “This account has not shared their email address with us” :(
(Oh, but it redirects to “Contact Through OpenID” — I don’t know exactly what’s that)

no there’s no way…