[Dovecot] smtp -auth with using clear text password

Hi

I am setting up a mailserver .. where clients need to authenticate to the mail server . The mta i am using is postfix . It is possible to use a file like this :

cat /etc/postfix/dovecote_passwd agnello:123456

where user is agnello and password is 123456

If you can please send me some reference links

thanks a ton

-- Regards Agnello D'souza