[imp] Compose Window Problem

[WebTeam]

Hi All,

We are running Linux 9.0 and recently installed the Horde 2.2.3 and IMP
3.2.1.
The server on which Horde/IMP is running is different from the Mailserver.
we want to use the Mailserver (192.168.1.1) to send/receive the mails while
WebInterface will run on another machine.
The receive mail/Inbox part is workin fine but the Compose is giving
problems

The Compose windows closes as soon it opens on some machines while on some
it stays.
The browser being used in all cases is IE.
What could be the reason for this behavior.

But anyways the mails are not getting sent.

The configuration that we have done is:

In file horde/config/horde.php
=====================

/**
 ** Mailer
 **/

// What method should we use for sending mail? Valid options are
// currently 'sendmail' and 'smtp'.
$conf['mailer']['type'] = 'smtp';

// An array holding any parameters that the Mail object will need to
// function correctly. For sendmail, this is mainly the sendmail_path
// option; SMTP requires at least a server and a port (if nonstandard).
// SMTP authentication can be enabled by setting the 'auth' parameter
// to true.
$conf['mailer']['params'] = array();
file://$conf['mailer']['params'] = array('sendmail_path' =>
'/usr/lib/sendmail');
$conf['mailer']['params'] = array('host' => '192.168.1.1');
$conf['mailer']['params'] = array('port' => '25');


in File horde/imp/config/servers.php
==========================
$servers['imap'] = array(
    'name' => '192.168.1.1',
    'server' => '192.168.1.1',
    'protocol' => 'imap',
    'port' => 143,
    'folders' => 'mail/',
    'namespace' => '',
    'maildomain' => 'iiml.ac.in',
    'smtphost' => '192.168.1.1',
    'realm' => '',
    'preferred' => ''
);

How can we prevent the Compose windows from closing on all machines?
And how to get the mail sending function to work?

Thanks in Advance,
Manish Gupta