Hello,
Internet forums do not store messages. That is done by SQL. Take this forum for example. You can go back to 2004 and find messages from when the forum first started still stored. IF the forum and hosting are good they will have backups of all the stuff from all times and be able to dig them up whenever they need to.
We still have old topics brought up and posts from when the old forum was up. That was well over 2 years ago.
Cheers,
Mak