Your mail client may notice you the following:

SMTP Error (550): Failed to set sender “someone@example.com” (Access denied – Invalid HELO name (See RFC2821 4.1.3)).

And the message sending is failed ! right ?

Here is the solution.

You should add smtp helo name in the configuration.

$config['smtp_helo_host'] = 'localhost';

Find the file config.inc.php from your mail client application, and add the line.

VestaCP: /etc/roundcubemail/config.inc.php

 

SMTP Error (550): Failed to set sender

 

Now login to your mail client and test the outgoing mail by sending one.

Enjoy !