Horde shows:
There was an error sending your message: Failed to add recipient: recipient@targetrecipient.com [SMTP: Invalid response code received from server (code: 550, response: Verification failed for No Such User Here" Sender verify failed)]

/var/log/exim_mainlog shows:
2010-03-28 18:47:46 H=localhost (userdomain.com) [127.0.0.1] sender verify fail for : No Such User Here"
2010-03-28 18:47:46 H=localhost (userdomain.com) [127.0.0.1] F= rejected RCPT : Sender verify failed

99.99999% of the time, you’ll see this issue when the Default Address is set to “fail”, making it unrouteable. In cPanel > Default Account, set the catch-all account to forward to another email address, and you’ll be all set.

# cat /etc/valiases/userdomain.com
*: ":fail: No Such User Here"

Such a setting would tell the server that the account doesn’t exist, causing the Sender Verify error.


[30-Jan-2009 14:07:11] Invalid response code received from server (421):
[30-Jan-2009 14:07:11] Invalid response code received from server (-1):
[30-Jan-2009 14:07:34 -0800] SMTP Error: SMTP error: Authentication failure: STARTTLS failed (Code: ) in /usr/local/cpanel/base/3rdparty/roundcube/program/steps/mail/func.inc on line 1248 (POST /3rdparty/roundcube/index.php?_task=mail&_action=send)
[30-Jan-2009 14:10:29] STARTTLS failed ():


Then there is an issue with the most recent Net-SMTP PHP module. To resolve this, edit the following file:


/usr/local/cpanel/base/3rdparty/roundcube/config/main.inc.php

and change

// SMTP username (if required) if you use %u as the username RoundCube
// will use the current username for login
$rcmail_config['smtp_user'] = '%u';

to this:


// SMTP username (if required) if you use %u as the username RoundCube
// will use the current username for login
$rcmail_config['smtp_user'] = '';