I have a virtual server running Debian Wheezy, and I am trying to configure it as a Postfix mail server. I haven't found though any easy to follow tutorial on how to secure Postfix... and my mail.log file is already full of requests from spammers for sure, since my server is only a few weeks old, and I haven't configured it yet.
So, I am looking for the proper Postfix configuration to accept emails going to my domains or going to other domains only if they are coming from my domains. I don't want Postfix to relay emails from joeblow@NotMyDomain1.com to MrSmith@NotMyDomain2.com.
Also, I would like my SMTP server to require a secure authentication to send emails.
However, let's say I own domains abc.com, def.com and xyz.com, then I want all emails coming from these domains to be relayed by my server if proper authentication is given, and I want all emails going to these domains to be relayed by the server.
And I don't want to restrict emails relaying by network address, since I may be on any network with my laptop, and I want to be able to send emails from it.
I have ssh access to my server, and I have Webmin on it. I don't mind using shell commands, but it would be nice to have a web interface to manage all this and more on my server... if anyone has a suggestion.