M365 group mailbox mail is invisible to personal mail tools

Mail sent to a Microsoft 365 group alias lives in the group's own mailbox. Graph /me/messages and the default ms-365-mcp-server mail tools only show copies where the signed-in user was also a direct recipient. A full-mailbox scan of about 4,000 messages found almost none of the 68 target threads, and replies sent as the group were missing too. An out-of-office reply to a thread you can't otherwise find is a strong hint that the conversation lives elsewhere. Check the To header for a group alias, then use the shared-mailbox tools (list-shared-mailbox-messages, list-shared-mailbox-folders), which did work against the group address, including its Sent Items.