We are using Exchange 2003 to handle e-mail popped from an ISP provider.
There is a user who is having mail bounced back with the message "recipient's mailbox is full". I checked the his mailbox size and it is only 259, 682 KB. There are no storage limits set. This only seems to happen if he is sending mail internally through Exchange. If he sends to an outside address, they receive the mail and he gets their reply.
The "mailbox full" error message seems to come from the ISP as their mail server address is stamped underneath the message. However, no messages are stored on the ISP server as they are popped to our Exchange server every 15 minutes.
I suppose we could set up his Outlook to pop directly from the ISP, but I can't understand why it's not working with Exchange.