If you have a Google Gmail account, you can relay mail from your home linux system. It's a good exercise in configuring Postfix with TLS and SASL. Plus, you will learn how to bring down the mail safely, using fetchmail with the "sslcertck" option. That is after you have verify and copied the necessary certificates. You'll learn all that from this tutorial, http://souptonuts.sourceforge.net/postfix_tutorial.html
, and you'll have Gmail running on your local Postfix MTA.