Hi Mike, You do have the choice… You can stay with shared mailboxes, acknowledging that they don’t work quite the way that you want, or move to Microsoft 365 groups. You can argue that Microsoft hasn’t done a good job of implementing Microsoft 365 groups (and 8 years after the introduction of groups, you might be right), but we don’t get to vote in how groups are developed. It seems to me that the most pressing and urgent mission for Groups is now in membership management rather than the kind of functionality that you might want, but Microsoft gets to make that call.

At the end of the day, you can ask Microsoft to make changes through your account representative – or move to find another solution. That’s choice too.

No.

It’s true that Outlook desktop doesn’t support sending email from shared mailboxes using proxy addresses that are not the primary SMTP address. It’s a MAPI thing, or so I believe.