Distribution list question

Is it possible to send email from outside to a group inside the domain? (from internet) What would I need to setup?

Subject: distribution list question

Once you set up your group document, you have the option of appending an internet address to it. Let’s say you set up a distribution list group, with 5 people, and your company domain is @xyz.com. Within the internet address field, of the group, youc an specifiy, test@xyz.com, or whatever localpart you want to assign, provided it’s not already in use. When an external user sends email to test@xyz.com, 5 seperate SMTP messages will be sent to the 5 users’ in the group. If you need any further help, let me know. Thanks.