@scottA82 It is probably best to reach out to your administrator (if this is a work account) or to Microsoft support (if this is a personal account). The one thing I can imagine, if this is a work account, is that your mailbox is indeed full. There's an underlying structure to your mailbox, with a lot of hidden folders, and I've seen cases where these hidden folders go over the limit (especially in situations where a mailbox is on so called "litigation hold").
