For example, using "www" in verbose mode I see:
HTSimplify.. `news:CxL5p8.8EL@nntpa.cb.att.com' into
............ `news:cxl5p8.8el@nntpa.cb.att.com'
....
HTNews: Looking for news:cxl5p8.8el@nntpa.cb.att.com
Connecting to NewsHost ... ...
....
HTNews: Sending NNTP command: ARTICLE <cxl5p8.8el@nntpa.cb.att.com>
NNTP Response: 430 No article by message-id <cxl5p8.8el@nntpa.cb.att.com>, sorry.
John Ellson
AT&T Bell Labs