Recently I've had messages get lost/deleted when I try to move them to another folder. If I use Mozilla, I'd drag-and-drop. If I use Squirrel, I'd mark and move-to-folder.
Some messages move OK, others get lost. The lost ones don't go to Trash, they just disappear. No errors, nothing in the logs.
I've got a theory that most the mail that gets lost on a move is either HTML or has 1+ attachments of any size. The problem doesn't seem to affect all folders of a mailbox/account, but it does seem to be a sticky problem - once a folder goes "bad", it stays bad. Not all users exhibit this problem.
Disk seems ok, etc... looking for debug ideas. Tks, D.