Also TO doesn't need to match. When you send to a group of BCC the envelope To has to specify the exact recipient, but the DATA doesn't. Similar with the envelo

Also TO doesn't need to match. When you send to a group of BCC the envelope To has to specify the exact recipient, but the DATA doesn't. Similar with the envelope From and the one in the DATA - also useful to control bounces or who gets a reply. Yeah I know the protocol and can do that manual, because I had to debug it often enough.