How to fix Roundcube SMTP Error (450) and Host not found in CWP

This is what i do when i found my server in Centos Web Panel cant send email and showing this error in roundcube.

"SMTP Error (450): failed to add the recipient "email@email.com" (4.7.1 <localhost>: Helo command rejected: Host not found)."

I was frustrated because i cant send email, it takes me almost 4 hours to find out what going on. Then i finaly fix it. this what i do

1. Login to your root and open this command : nano /usr/local/apache/htdocs/roundcube/config/main.inc.php

Find:

$rcmail_config['default_host'] = '%n';

$rcmail_config['smtp_server'] = '%h';

Change to :

$rcmail_config['default_host'] = '';

$rcmail_config['smtp_server'] = '';

Then Restart postfix

service postfix restart

If this error still preceed. you might wanna rebuild mail server in CWP.admin

[caption id="attachment_1809" align="aligncenter" width="987"] Rebuild Mailserver[/caption]

or you can rebuild apache server in Apache Settings



Iam using Apache & Varnish cache & Nginx reverse proxy. You can choose whatever you like. Dont forget to Rebuild Virtual Hosts after that otherwise your website wont run.