[horde] Mailer SMTP option not working

[Jeff Tipton]

Hi,

I have my mail system and Horde on separate machines on my LAN, so I set 
$conf['mailer']['type'] = 'smtp';
But when I'm trying to send a message from IMP, it fails with "Error 
when communicating with the server". When I look up the mail system's 
logs, no attempt to log in appears.

 From Horde's host, I can telnet to my mailsystem and send a message. 
This is the "Mailer" part of my config:

$conf['mailer']['params']['host'] = 'hostname.domainname.local';
$conf['mailer']['params']['port'] = 25;
$conf['mailer']['params']['auth'] = 'PLAIN';
$conf['mailer']['type'] = 'smtp';

This is the contents of horde/imp/config/backends.local.php:

$servers['imap'] = array(
     'disabled' => false,
     'name' => 'IMAP Server',
     'hostspec' => '192.168.2.11',
     'hordeauth' => full,
     'protocol' => 'imap',
     'port' => 993,
     'secure' => ssl,
     'maildomain' => 'domainname.tld',
     'smtphost' => 'hostname.domainname.local',
     'smtpport' => 25,
     'quota' => array(
         'driver' => 'imap',
         'params' => array(
             'hide_when_unlimited' => true,
             'unit' => 'MB'
         )
     ),
     'acl' => true,
     'cache' => false,
);
?>

Although I set Horde's log level to "debug", when sending I only get 
these lines with [imp] mark:

Sep 25 12:41:56 www HORDE: [imp] Load config file (conf.php; app: imp) 
[pid 61971 on line 861 of "/usr/local/share/pear/Horde.php"]
Sep 25 12:41:57 www HORDE: [imp] Load config file (nls.php; app: horde) 
[pid 61971 on line 861 of "/usr/local/share/pear/Horde.php"]
Sep 25 12:41:57 www HORDE: [imp] Max memory usage: 21233664 bytes [pid 
61971 on line 474 of "/usr/local/share/pear/Horde/Registry.php"]

Any ideas of how to solve this?
Thanks.