> For Sendmail compatibility, Postfix does not show the first header > line. I suggest that you put new content further down in the message.
Does "the first header line" refer to the (locally added) Received:
header? If so, sendmail doesn't provide that to a milter as it is
not sent by the client. However, sendmail is supposed to follow
this description:
* For smfi_chgheader, filter order is important. Later filters
will see the header changes made by earlier ones.
