imap_open Error

I'm using the following code to try to open a stream to access my email: $user_id = "userid"; $password = "password"; $inbox = @imap_open("{mail.host.com:143}INBOX", $user_id, $password); I've verified the correct username, password, hostname combination by setting up an IMAP account through Outlook Express. However, whenever I try and open the page that this code sits on I get a "The Page Cannot Be Displayed" error. Specifically, it says that it cannot find the server or DNS error. I can comment out the imap_open line and the page will load fine. Also, I've asked my host and verified that the imap functions are available as part of PHP. I can't figure out why this is happening. Any help would be greatly appreciated. Thanks, Brian