IMAP help

[xpressmail]

i have an emailserver (sendmail) coded using php.But i cannot read mails in my machine using imap function in php. when i use imap_open function in php i am getting a warning cannot open stream... i am using redhat9 . DO u need any further information . please help . its urgent . its apart of project work at college. i have to submitt it within 2 days . Is there any configuration for imap .
I am able to access mails using evolution and imap://user@localhost. My host name is xpressmail.com hence
imap://[e-mail] . but its notworking when i use php function
Pls help

<?php

$server = "mail.com";

$user = "john";

$pass = "mypass";

$conn = @imap_open("{$server/imap}INBOX", $user, $pass)

or die("Connection to server failed");

?>

this code isnot working .
I am getting warning message could open stream mail.com ...