receiving email errors

My email tells me I am receiving a message which has so far taken 10 minutes to receive. This has been happening all day but then ends up with an error code......0x800ccc0b. I have restarted my computer and still nothing. The other error is 0x8004210e and tells me my mailbox is temporarily unavailable because another email message is being delivered to it or another mail application is accessing it. ERR mailbox locked.......help??