Please help to resolve the following error:

Unable to send or receive messages for the Tto.com (chuan) account. Header download for the 'Inbox' folder did not complete. The host 'mail.tto.com.sg' could not be found. Please verify that you have entered the server name correctly.

Server Response: Your IMAP command could not be sent to the server, due to non-network errors. This could, for example, indicate a lack of memory on your system.
Server: 'mail.tto.com.sg'
Windows Live Mail Error ID: 0x800CCC0E
Protocol: IMAP
Port: 143
Secure(SSL): No

Thanks!