> What I'd like to do is tell (Win)HTTrack to
> acknowledge that the project includes that site, so
> that it will put on hold the links pointing to it
> instead of downloading the "account suspended" page
> for all the links, in order to complete the job once
> the site is back online (if ever).

Best way is probably to exclude the down sites with scan rules
(-www.example.com/* as last rule), and remove the rule when the site is up
again, selecting "Continue an interrupted mirror".