Microsoft 365 Group email only being delivered to external addresses

I am the admin for my small nonprofit (we have a small full-time staff, with mostly outside volunteers). A while ago I had created a mailing list (actually, a Group Distribution List) with a few internal emails, but mostly external (e.g. @gmail.com) addresses. It was working fine.

I wanted to upgrade to making that a MS Teams group, so I deleted the Distribution List, and created a team within MS Teams. I added all the outside users as guest users, along with the couple internal users, and that (apparently) went fine. The group is now a Microsoft 365 group, with MS Teams status as "connected." I can see the users in Microsoft 365 admin center, as well as everyone listed in Active Users and Guest Users. Everything looks fine in the Exchange admin center as well.

However - I just discovered that when someone emails the group email, email is surprisingly not delivered to the internal email accounts! The external guest emails are getting their emails. I looked in the internal users' accounts when they are logged into Outlook/Teams and I can't find any place those emails might have gone.

Is this behavior expected? Am I missing some option I need to turn on so internal users receive email send to the group email address?

Solution 1:

Looks like this was a MS bug. I went into https://admin.microsoft.com/, and clicked on Groups → Active Groups → <group name> (Settings pane opens) → Settings tab. I unchecked Send copies of group conversations and events to group members, clicked Save; rechecked that option, then clicked Save again. Group emails are now flowing through to everyone.

Solution 2:

This is by design, and we could refer to the official document: https://docs.microsoft.com/en-us/microsoft-365/admin/create-groups/manage-groups?view=o365-worldwide

When you use the admin center to create a group, by default users do not get copies of group emails and meeting invitations sent to their inboxes. They'll need to go to the group to see conversations and meetings. You can change this setting in the admin center. When you turn this setting on, group members will get a copy of group emails and meeting invitations sent to their Outlook Inbox. They can read and delete this copy of the email and not affect anyone else. In the Group inbox, a copy of the email still exists.