You might want to send a preview copy of your email newsletter to your team members, to get their feedback before sending to your main list. The "Send preview" button will only send a preview copy of your email to your own address. In order to send a copy to a group, you will need to create a test mailing list.
1. Create a new mailing list
Create a new mailing list and call it "Team members" or "Test mailing list". You should add your team members email addresses, and anyone else who'd like to preview your newsletters
2. Create an email newsletter for the "Team members" mailing list
Create an email newsletter for this new mailing list. Write it as if it were going to be sent to your main mailing list. Once you are ready to show your work to your team, press the "Send this email" button. They will each receive a copy in their inbox.
3. Duplicate the email newsletter for your main mailing list
Once you have collated feedback from your team, you are ready to create your real email newsletter. Find and duplicate your sent email newsletter for your main mailing list. Once duplicated, you can make your changes, preview and send.