Outlook Groups: who can send an email?

hi GeneL56​ I think the confusion here is between being a member of the group and being a trusted sender.

In Outlook Groups, the "Trusted Sender" setting generally controls whether messages from outside the group are treated as trusted or allowed through certain moderation/filtering rules. It doesn't necessarily mean that only trusted senders can send messages to the group.

If someone is already a member of the group, they may still be able to send messages to the group even if they aren't listed as a trusted sender. The trusted sender setting is more relevant to how messages from non-members or external senders are handled.

So, in your case, the member being able to send an email to the group may actually be expected behavior. If your goal is to prevent specific members from sending messages to the group, the available controls may be more limited depending on the type of Outlook group you're using.

It would be useful to confirm whether this is an Outlook.com personal group or a Microsoft 365 group in a work/school tenant, as the behavior and available settings are different.