When your group is first set up, any member of the group can send out messages by e-mailing the mailing list address. If you’d like to change this, you can modify the settings to give only certain people posting permissions.
Restrict who can Send E-mail
To turn off the ability of members to send e-mail to the list, you’ll need to change one setting. Go into your Google Groups and choose Manage Group
Choose “Posting permissions” at the right.
Under Post, you can uncheck the box for “All members of the group” to remove the ability of members to post.
DO NOT check “Anyone on the web”! That will give anyone in the world the ability to send to your group and bring in a lot of spam.
Once you set this, you can allow people to send messages either by making them managers, or specifically giving them access to post.
Click Save to save your changes.
Granting Members Permission to Post
If you’ve removed the ability of members to send messages to your group by default, you can still give them the ability to send messages without giving them access to anything else. To do so, click “Manage members” for your group.
Check the box next to the members that you’d like to allow to post. Then, from the Actions menu, choose “Set posting permission” and “Override - Allow Posting”
To remove their added access, check the box next to the user, and choose “Default group policy” from the Actions -> Set posting permission menu.
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