Hi.
I have a VPS running CentOS and Webmin CP.
I configured Postfix Mail Server and I can send and receive emails in Webmin, but I couldn't set up POP3 and SMTP.
I tried to configure Dovecot IMAP/POP3 Server, but when I try to connect to the POP3 or SMTP, it says user or pass is incorrect.

I couldn't find any useful tutorial.

How can I set them up?

Thanks.