Here is a little known issue with archived folders and the .OST file. I learned this when addressing the same issue for an administrator. When you set up an outlook email account on a PC for the first time and set it to use cached mode, then the “modified” date of ALL emails in that account changes to the date that outlook created the .OST file. Unfortunately the auto-archive feature of Outlook is based on MODIFIED date, not RECEIVED date. So if this account was set up recently, say within the last week or so, and the auto-archive feature is set to archive monthly or more, then nothing will archive until that time period has passed from the date the .OST file was created. Fun, huh?