Enable access to Webmail after VestaCP is installed

[ipcompany]

Hello.

I have a VestaCP only installed with email service (Exim, Dovecot and Crond), but now I need access to Webmail.

How can I make Webmail work after VestaCP is already running? When you access http://191.243.199.159/webmail, you acknowledge this error: 554 SMTP synchronization error

Thank you.

Daniel Guidolin