whitelisting mailing lists with dccproc

I subscribe to some yahoo run mailing lists. I can normally identify
(for sorting purposes) mail from these sources by either the subject
line (a regexp match) or the to: address

If I put 

    ok env-to	T-U-G@yahoogroups.com

in my whiteclnt file, it obviously doesn't match as dccproc doesn't
have access to the env information. 

    ok  to T-U-G@yahoogroups.com

isn't valid, because there is no such match as "to" :-(

What should I do to whitelist mail from such sources ?

Thanks,

 Nick