Wietse:
> The first line that is "not a header" is considered to be part of
> the message body.
>
> Postfix may or may not prepend a blank line to this non-header
> line (it always, did but then it was found that it is better not
> to insert a blank line in malformed attachments. As of 20070112
> Postfix inserts the missing blank line only after the primary
> message header).
Murray S. Kucherawy:
> Does this go for a header field in which there's a space between
> the name and the colon as well? For example:
>
> MIME-Version : 1.0
Postfix permits whitespace between header name and colon, as per
RFC 2822 Section 4.5 (see comment in global/is_header.c).
The Postfix MIME parser trims the space to simplify message handling
further down the line, even if it may break a digital signature
(see comment in mime_state.c:mime_state_update()).
The way that Postfix is built it will never send this obsolete
header form into a signing algorithm.
> Sendmail, for example, corrects this and accepts it without starting
> the body there.
>
> I'm collecting enough of these results from open source and
> commercial MTAs alike that I'll probably seek to publish a "best
> current practices" about it.
Wietse
