Manage External Mail Sent to Groups
Owners have the ability to enable or disable non-members from sending messages to your Office 365 Group.
- In a web browser, navigate to
portal.office.com, sign in, and select Outlook.
- Under the Groups section, select the name of the group.
- In the top right corner of the window, click on the gear icon to open the Settings section.
- Select Edit Group.
Manage Non-Members Ability to Send to a Group
- Check/Uncheck the Let people outside the organization email the group box in the group settings.