David,
The posts are there.
Keep the old url and just strip the "sdm." part of it and try again. Thanks to Tilmann "Magic" Singer you'll be redirected to the right post on the new site!
Try this:
https://openacs.org/forums/message-view?message_id=21870
(Same thing if someone tries to get https://openacs.org/bboard - they will be redirected to our new forum index page.)
Dunno about search. You cannot search for posts by name in the message header, it seems...
