If you are a Roundcube Webmail user, you might have faced this error and may have stuck when you have to send an urgent email. You need not worry, and if you are an admin you will be able to easily resolve it. 

if you are sending mails from Round Cube and while trying you are getting this error.

“SMTP Error (535): Authentication failed”

All you got to do to fix this is to make a change  in the RoundCube config file. In a normal server, roundcube config file, can be accessed through this path:  “/usr/share/roundcube/config/main.inc.php”

To fix the error you are getting, you will need to change the below value and save the config file.

$rcmail_config[‘smtp_user’] = ‘%u’;

to

$rcmail_config[‘smtp_user’] = ”;

Now, this should fix your issues and you should be able to send mails without any issues. 

If the problem persists, talk to our server helpdesk support experts to fix any issues you have. 

Gain comprehensive offers, cPanel Server Management services and a wide range of server administration support on all cPanel related works. 

Nixtree also provides other Server Management services, Plugin Development for control panel based servers, Server Security Services, Disaster Recovery Services and more