Roberto Olie - 2013-05-16

I state that I am not practical of Ubuntu and PostFix. Typically I use Windows and MailEnable
I need to configure a mail server on Ubuntu with Webmin and Postfix, but I can not figure out how to do the following very simple things.
My need is to create a mail server with one or more domains, and one or more e-mail accounts for each domain: I need to activate the authentication of outgoing mail via username and password (the same as input) and be able to send email from other host on the web, using the mail server's host name
1. How can I create a domain? (eg.
2. How can I create a mailbox on a domain, with its password? (eg.
3. How can I set up the server so that it accepts the use SMTP from any PC on the web?
4. How can I set the outgoing mail authentication with the same credentials of the incoming? (address as username and password)
Can someone explain how to do? Preferably via the webmin interface for postfix, but that's okay also manually editing the configuration file.