Most likely, your mailbox is full. So when people try to send emails, the server sends them a message back saying that it can't receive anymore emails because your mailbox is full. If you connect with POP, this means you haven't setup your mail program correctly, because it should be deleting old messages off the server when it downloads them. So speak with your local tech support or see our Email Setup Guide for some tips. If you connect with IMAP, you may need us to increase your mailbox size, to allow for more space for your growing needs. Please contact us immediately so we can help.