Could not send message to SMTP server. Check you have access to send messages via the server and that all To/CC/BCC addresses are valid\nError: SMTP Server rejected email. Returned:530 Authentication required.
Go to /var/www/atmail/libs/Atmail/ modify Config.php and check that 'smtphost' variable equal to 'localhost':
'smtphost' => 'localhost',
