First look at the thread called "Re: Yahoo password 
problems" from Kjell, which may be interesting for 
backuping egroups/yahoo groups.

Then, if images are missing, there are two cases:

- images refers to an external address, which has not 
been downloaded - in this case add proper filters, 
that is, something like '+*.gif +*.jpg +*.jpeg +*.pn' 
in the 'Options'/'Scan rules' section.

- images are missing because of some javascript 
routines/onclick function : this case is - 
unfortunately - not so obvious, as HTTrack can not 
analyze *complex* javascript code