Making a google group email address publicly reachable

1. Create the group email address, choose the members, etc. in groups.google.com
2. Navigate to admin.google.com, then Groups and hover the mouse over the email address that you’ve created. Choose settings/preferences. Select “External” for the value of “who can publish entries or posts”.

Like this:

Support link: https://support.google.com/a/answer/167097