Hi,
I installed roundcube version rc1. After having configured main.inc.php and
db.inc.php, I was unable to send any emails.
I had a problem with the postfix server, the error was : 504 5.5.2
<localhost: Helo command rejected: need fully-qualified hostname.

In order to solve this problem I modified the file
program/include/rcube_smtp.inc. I replaced the line 75 ( $helo_host =
!empty($_SERVER['server_name']) ? $_SERVER['server_name'] : 'localhost';)
with this :

I've got the similar problem and it was solved by replacing the variable name with itscapitals (as they are in phpinfo()):

$helo_host = !empty($_SERVER['SERVER_NAME']) ? $_SERVER['SERVER_NAME'] : 'localhost';)

It is a little bit strange but it works.

if ( !empty($CONFIG['helo_host']) ) {
  $helo_host = $CONFIG['helo_host'];
}
elseif ( !empty($_SERVER['server_name']) ){
  $helo_host = $_SERVER['server_name'];
}
else {
  $helo_host = 'localhost';
}

Then in main.inc.php I added the line :

$rcmail_config['helo_host']= 'myhostname';

It finally worked for me! ;)

Hope this helps
--
________________________________________________

Renaud Hager
Administrateur Système et Réseaux
UMR 8504
13 rue du four 75006 Paris