In order to receive the confirmation code/link sent by Google, your group must allow external senders.
How to manage the email delivery settings for Google Groups and choose how many emails members of the group recieve from that group.
How to verify visibility settings for individual Google Groups.
You can join a Google Group to take part in collaboration with a team.
Sending on behalf of a Google Group to post anonymously as the group.
Group User management is the responsibility of the group managers, and is updated through the Groups UI.
Reasons why someone would not recieve a copy of an email that they sent to a distribution list.