Additional sender list
NOTE: The additional senders list is for paid groups only. It does not apply to groups on the free plan.
Here's a more granular way to select who can send to your group. You can allow specific non-group members to send messages. They won't receive group messages, but they will receive replies to their messages as threaded conversations.
-
Login, click to select the group where you want to make changes, click Settings:

-
Scroll down to Message Flow and click Manage additional senders:

-
Click Add to either add individual email addresses (1), or allow anyone from a specific domain (2) by adding *@domain (as a wildcard email address):

-
Click Add additional senders and Gaggle Mail shows you the added email addresses/wildcards:




