Q: Why do you clear Classified posts after 90 days?
A: In order that the forum can run smoothly it is necessary to periodically remove or archive old posts. Typically, the Classifieds forum thread is "pruned" every so often removing all posts over 90 days old, all other forums have an automatic 1000 day archive system in place.
It would be helpful (if you sell an item), you got back into your original post and click the "modify" button, and select "Full Edit". Edit your title so the following is included "- SOLD". This means the admin team can quickly review the sold items and remove them from the forum.