SharePoint Online (365) no longer sending share notifications to M365 Groups

BrianRMI 

We had this problem too.

This is how you solve it:

First we need to allow emails from people outside of the organization.

In the admin center go to Teams & groups -> Active Teams & groups and find your M365 Group.

Click on it, then under "Settings" check "Let people outside the organization email this team".

We don't want people outside of the organization to email our groups so we need to restrict it later. First we need to add Sharepoint as a mail contact (because everything you share in OneDrive will be shared from "email address removed for privacy reasons" now and not the user anymore).

In the Exchange admin center go to recipients -> contacts and click on "Add a mail contact". Fill out the information and make sure to put email address removed for privacy reasons as the external email address.

In Exchange, find your group and edit the delivery management. Set it to "Only senders in the following list". Then add your new Sharepoint contact. You should be able to find it by searching for either the email or the name you gave it.

The problem should be solved. 

Keep in mind, that you also have to add people to the delivery management list who should be allowed to send emails to the group.