Does "the To field of the incoming message" mean the RCPT TO argument of the LMTP session? Or the "To:" header of the message. I think it should mean the former, since the latter needn't be related at all, if the list permits BCC.
Does "the To field of the incoming message" mean the RCPT TO argument of the LMTP session? Or the "To:" header of the message. I think it should mean the former, since the latter needn't be related at all, if the list permits BCC.