Why am I rereceiving old messages (every single one I’ve ever recieived) from a linked email account?

My account is linked to my personal website's email account, so all my emails come through hotmail. For about a month, every week / two weeks I have received every email I have ever received in that account into my hotmail account as unread, even when these emails have been read or deleted they will pop back into my account a few days later. Is it something to do with the way the link is established, or a glitch in the system which means its happening by accident? In any event, how do I make it stop?!!