If you are interested this is what I found out and how I fixed our install, it's now working perfectly!
 
The problem was that RoundCube was doing the EHLO to our mail server and claiming to be localhost (which it's not) instead of the actual hostname (roundcube.whatever.com). Our mail server saw this as a SPAM attempt in which the spammer was claiming to be localhost which is what they do many times.
 
To fix this, I did some digging in the code and found a file eventually named rcube_smtp.inc which is in the program/include directory.
 
I found this line:
$helo_host = !empty($_SERVER['server_name']) ? $_SERVER['server_name'] : 'localhost';
 
and changed it to:
$helo_host = !empty($_SERVER['server_name']) ? $_SERVER['server_name'] : 'roundcube.mydomain.com';
 
Where roundcube.mydomain.com is the full hostname of the server running the RoundCube code.
 
Hope this helps!
 
--Todd
 
--
Start Your Own Internet Service!
http://www.YourOwnISP.com
 
----- Original Message -----
From: Brady J. Frey
To: users@lists.roundcube.net
Sent: Thursday, February 09, 2006 1:59 PM
Subject: [RoundCube Users] Outbound email fails via smtp

I've attempted to program all settings into our server for outbound email usage, but to no avail. Currently we're a Cyrus OS X server, with smtp, password authorization required for outbound sending of messages. Now, I get the %u/p parts, and I have it set to the proper smtp address... should I not just be using 'LOGIN' as the password protocal? I've essentially tried all, and none seem to work, I'm wondering if there's a different outbound preference I should put in there that I'm not seeing? Thanks all!

p.s. -- I second the archival request.

--
Brady J. Frey
creative director // dotfive

www.dotfive.com