This article was previously published under Q278637
When you use Microsoft Outlook Express to send and receive mail to a Post Office Protocol 3 (POP3) or Internet Message Access Protocol (IMAP) server running Exchange 2000 Server or Exchange Server 2003, you may receive the following error message:
Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity. Account: 'account name', Server:'server', Protocol: POP3, Port 110, Secure (SSL); No, Error Number: 0x800CCC0F
Additionally, if you try to telnet to the server and access either port 110 (POP3) or 143 (IMAP), when the POP3 or IMAP banner appears, you are disconnected immediately, and you receive the following error message:
Connection to host lost.
This problem may occur if the Exchange Server administrator has enabled bandwidth throttling in Exchange 2000 Server or in Exchange Server 2003.
To resolve this problem, contact the Exchange Server administrator to see if he or she has to disable bandwidth throttling on the Exchange server. If you are the administrator of the Exchange server, follow these steps to disable bandwidth throttling on an Exchange server:
Click Start, point to Programs, point to Administrative Tools, and then click Internet Services (IIS) Manager.
Right-click the Web sites, and then click Properties.
Click the Performance tab, and then clear the Limit total network bandwidth available for all Web sites on this server option.
Note POP3 and IMAP capabilities are not affected when you enable bandwidth throttling on each Web site. The Enable Bandwidth Throttling option is located on the Performance tab of each Web site.
For more information about how to enable bandwidth throttling, search for the words "bandwidth throttling" in the following Microsoft Help and Support Center Web site: