Planning upgrade to 2107, and the pre-req check reported backlogged inboxes. My auth\statesys.box\corrupted has a number of files in it. Some, within the last couple of days, others going a few months back, or more.
The main philosophy I've seen in my research is to backup the files elsewhere, and delete from any inbox, if the files are obviously not being processed, but wanted to verify on this one.