I've came across this issue twice now at work, and cannot understand why this is happening. The issue we're having is, certain emails are deleting themselves from the inbox, but only ones that have been read. I've tried the 'View unread messages' option, which got rid of ALL emails besides ones that haven't been read, but it seems to only be certain emails. For example, the user has 4 unread emails in her inbox now, and 142 read ones. If she clicks on one of the already read ones, it disappears, not in the Deleted Items folder, not anywhere. It happens with the unread ones too.
Anyone experienced this before?